diff --git a/cleantalk.php b/cleantalk.php
index 95e921655..e7b61a6e1 100644
--- a/cleantalk.php
+++ b/cleantalk.php
@@ -1001,7 +1001,6 @@ function apbct_sfw__check()
                 APBCT_TBL_FIREWALL_LOG,
                 APBCT_TBL_AC_LOG,
                 array(
-                    'api_key'    => $apbct->api_key,
                     'view_limit' => $apbct->settings['sfw__anti_flood__view_limit'],
                     'apbct'      => $apbct,
                 )
diff --git a/lib/Cleantalk/ApbctWP/Firewall/AntiFlood.php b/lib/Cleantalk/ApbctWP/Firewall/AntiFlood.php
index b05e4cfe3..308c47a94 100644
--- a/lib/Cleantalk/ApbctWP/Firewall/AntiFlood.php
+++ b/lib/Cleantalk/ApbctWP/Firewall/AntiFlood.php
@@ -16,12 +16,13 @@
  */
 class AntiFlood extends \Cleantalk\Common\Firewall\FirewallModule
 {
+    const PASS_TOKEN_TTL = 60;
+
     public $module_name = 'ANTIFLOOD';
 
     private $db__table__ac_logs;
     private $db__table__ac_ua_bl;
 
-    private $api_key = '';
     private $view_limit = 20;
     private $apbct = array();
     private $store_interval = 60;
@@ -112,13 +113,14 @@ public function check()
             }
 
             // Passed
-            if (Cookie::get('apbct_antiflood_passed') === md5($current_ip . $this->api_key)) {
+            if ($this->consumePassToken(Cookie::get('apbct_antiflood_passed'), $current_ip)) {
                 if ( ! headers_sent()) {
                     Cookie::set('apbct_antiflood_passed', '0', time() - 86400, '/', '', null, true);
                 }
 
                 // Do logging an one passed request
                 $this->updateLog($current_ip, 'PASS_ANTIFLOOD');
+                $this->updateAcLog();
 
                 $results[] = array('ip' => $current_ip, 'is_personal' => false, 'status' => 'PASS_ANTIFLOOD',);
 
@@ -229,6 +231,7 @@ public function diePage($result)
 
         // File exists?
         if (file_exists(CLEANTALK_PLUGIN_DIR . 'lib/Cleantalk/ApbctWP/Firewall/die_page_antiflood.html')) {
+            $pass_token = $this->createPassToken($result['ip']);
             $this->sfw_die_page = file_get_contents(
                 CLEANTALK_PLUGIN_DIR . 'lib/Cleantalk/ApbctWP/Firewall/die_page_antiflood.html'
             );
@@ -269,7 +272,7 @@ public function diePage($result)
                 '{SERVICE_ID}'                     => esc_html($this->apbct->data['service_id']) . ', ' . esc_html($net_count),
                 '{HOST}'                           => get_home_url() . ', ' . APBCT_VERSION,
                 '{GENERATED}'                      => '<p>The page was generated at&nbsp;' . date('D, d M Y H:i:s') . "</p>",
-                '{COOKIE_ANTIFLOOD_PASSED}'        => md5($result['ip'] . $this->api_key),
+                '{COOKIE_ANTIFLOOD_PASSED}'        => $pass_token,
                 '{SCRIPT_URL}'                     => esc_url($js_url),
 
                 // Custom Logo
@@ -332,6 +335,65 @@ public function printDiePage()
         die("IP BLACKLISTED. Blocked by AntiFlood " . $this->apbct->stats['last_sfw_block']['ip']);
     }
 
+    /**
+     * Issue a short-lived pass token and persist it for a single atomic use.
+     *
+     * @param string $ip
+     * @return string
+     */
+    private function createPassToken($ip)
+    {
+        if (function_exists('random_bytes')) {
+            $token = bin2hex(random_bytes(32));
+        } else {
+            $token = hash('sha256', wp_generate_password(64, false, false));
+        }
+
+        $token_id = md5('antiflood_pass:' . $token);
+        $expires  = time() + self::PASS_TOKEN_TTL;
+        $query    = "INSERT INTO " . $this->db__table__ac_logs . "
+            SET id = %s, ip = %s, entries = 0, interval_start = %d, ua = ''";
+
+        $this->db->prepare($query, array($token_id, $ip, $expires));
+        $result = $this->db->execute($this->db->getQuery());
+
+        if ( ! is_int($result) || $result < 1) {
+            error_log('CleanTalk AntiFlood: failed to store a one-time pass token.');
+            return '';
+        }
+
+        return $token;
+    }
+
+    /**
+     * Atomically consume a pass token bound to the issuing IP.
+     *
+     * @param mixed $token
+     * @param string $ip
+     * @return bool
+     */
+    private function consumePassToken($token, $ip)
+    {
+        if ( ! is_string($token) || ! preg_match('/^[a-f0-9]{64}$/i', $token)) {
+            return false;
+        }
+
+        $token_id = md5('antiflood_pass:' . strtolower($token));
+        $query    = "DELETE FROM " . $this->db__table__ac_logs . "
+            WHERE id = %s AND ip = %s AND interval_start > %d AND entries = 0
+            LIMIT 1";
+
+        $this->db->prepare($query, array($token_id, $ip, time()));
+        $result = $this->db->execute($this->db->getQuery());
+
+        if ($result === false) {
+            error_log('CleanTalk AntiFlood: failed to consume a one-time pass token.');
+            return false;
+        }
+
+        return $result === 1;
+    }
+
     private function checkExclusions()
     {
         $allowed_roles = array('administrator', 'editor');
diff --git a/lib/Cleantalk/ApbctWP/Firewall/die_page_antiflood.html b/lib/Cleantalk/ApbctWP/Firewall/die_page_antiflood.html
index faa0b12fe..eb687670b 100644
--- a/lib/Cleantalk/ApbctWP/Firewall/die_page_antiflood.html
+++ b/lib/Cleantalk/ApbctWP/Firewall/die_page_antiflood.html
@@ -230,7 +230,7 @@ <h1 class='main'>{SFW_DIE_NOTICE_IP}<a href='https://cleantalk.org/blacklists/{R
 
 		setTimeout( function(){
 			var date = new Date;
-			date.setDate(date.getDate() + 30);
+			date.setTime(date.getTime() + 60000);
 			ctSetCookie(
 				[
 					['apbct_antiflood_passed', escape('{COOKIE_ANTIFLOOD_PASSED}'), date.toUTCString()]
diff --git a/tests/ApbctWP/Firewall/TestAntiFlood.php b/tests/ApbctWP/Firewall/TestAntiFlood.php
new file mode 100644
index 000000000..8db6e5328
--- /dev/null
+++ b/tests/ApbctWP/Firewall/TestAntiFlood.php
@@ -0,0 +1,131 @@
+<?php
+
+use Cleantalk\ApbctWP\Firewall\AntiFlood;
+use Cleantalk\ApbctWP\Variables\Cookie;
+use PHPUnit\Framework\TestCase;
+
+class TestAntiFlood extends TestCase
+{
+    private $initialApbct;
+    private $initialCookie;
+    private $initialCookieVariables;
+    private $initialHttpUserAgent;
+
+    public function setUp(): void
+    {
+        global $apbct;
+
+        $this->initialApbct = isset($apbct) ? $apbct : null;
+        $this->initialCookie = $_COOKIE;
+        $this->initialCookieVariables = Cookie::getInstance()->variables;
+        $this->initialHttpUserAgent = isset($_SERVER['HTTP_USER_AGENT']) ? $_SERVER['HTTP_USER_AGENT'] : null;
+
+        $apbct = (object) array(
+            'key_is_ok' => 1,
+            'api_key'   => 'test_api_key',
+            'data'      => array(
+                'key_is_ok'    => 1,
+                'cookies_type' => 'native',
+            ),
+        );
+
+        $_COOKIE = array();
+        Cookie::getInstance()->variables = array();
+        $_SERVER['HTTP_USER_AGENT'] = 'phpunit-agent';
+    }
+
+    public function tearDown(): void
+    {
+        global $apbct;
+
+        if ($this->initialApbct === null) {
+            unset($apbct);
+        } else {
+            $apbct = $this->initialApbct;
+        }
+
+        $_COOKIE = $this->initialCookie;
+        Cookie::getInstance()->variables = $this->initialCookieVariables;
+
+        if ($this->initialHttpUserAgent === null) {
+            unset($_SERVER['HTTP_USER_AGENT']);
+        } else {
+            $_SERVER['HTTP_USER_AGENT'] = $this->initialHttpUserAgent;
+        }
+    }
+
+    public function testPassTokenCanBeConsumedOnlyOnceAndCountsTowardTheLimit(): void
+    {
+        $prepared_query = '';
+        $prepared_vars = array();
+        $pass_consumptions = 0;
+        $executed_queries = array();
+
+        $db = $this->getMockBuilder(stdClass::class)
+            ->setMethods(array('fetchAll', 'prepare', 'getQuery', 'execute'))
+            ->getMock();
+
+        $db->method('fetchAll')->willReturnCallback(function ($query) {
+            return strpos($query, 'ORDER BY') !== false
+                ? array()
+                : array(array('total_count' => 1));
+        });
+        $db->method('prepare')->willReturnCallback(function ($query, $vars) use (&$prepared_query, &$prepared_vars) {
+            $prepared_query = $query;
+            $prepared_vars = $vars;
+        });
+        $db->method('getQuery')->willReturnCallback(function () use (&$prepared_query) {
+            return $prepared_query;
+        });
+        $db->method('execute')->willReturnCallback(function ($query) use (
+            &$pass_consumptions,
+            &$executed_queries,
+            &$prepared_query,
+            &$prepared_vars
+        ) {
+            $executed_queries[] = $query;
+
+            if (strpos($query, 'DELETE FROM ac_logs') !== false) {
+                $pass_consumptions++;
+                return $pass_consumptions === 1 ? 1 : 0;
+            }
+
+            return 1;
+        });
+
+        $module = new AntiFlood(
+            'firewall_log',
+            'ac_logs',
+            array(
+                'api_key'       => 'test_api_key',
+                'view_limit'    => 1,
+                'chance_to_clean' => 0,
+            )
+        );
+        $module->setDb($db);
+        $module->setIpArray(array('real' => '203.0.113.10'));
+
+        $create_token = new ReflectionMethod(AntiFlood::class, 'createPassToken');
+        $create_token->setAccessible(true);
+        $token = $create_token->invoke($module, '203.0.113.10');
+
+        $this->assertSame(1, preg_match('/^[a-f0-9]{64}$/', $token));
+        $this->assertStringContainsString('INSERT INTO ac_logs', $prepared_query);
+        $this->assertSame(md5('antiflood_pass:' . $token), $prepared_vars[0]);
+        $this->assertSame('203.0.113.10', $prepared_vars[1]);
+
+        $_COOKIE[apbct__get_cookie_prefix() . 'apbct_antiflood_passed'] = $token;
+
+        $first_result = $module->check();
+        $this->assertSame('PASS_ANTIFLOOD', $first_result[0]['status']);
+        $this->assertSame(1, $pass_consumptions);
+
+        // A new request can replay the browser cookie, but the server-side row is gone.
+        Cookie::getInstance()->variables = array();
+        $second_result = $module->check();
+
+        $this->assertSame('DENY_ANTIFLOOD', $second_result[0]['status']);
+        $this->assertSame(2, $pass_consumptions);
+        $this->assertStringContainsString('entries = 1', implode("\n", $executed_queries));
+    }
+}