    public function tableCleanup(int $maxInactiveMinutes = 30)
    {
        $now = new \DateTime();
        $minutesBack = new \DateInterval('PT' . $maxInactiveMinutes . 'M');
        $timestamp = $now->sub($minutesBack)->format('Y-m-d H:i:s');

        $sql = 'DELETE FROM '.TBL_SESSIONS.'
                 WHERE ses_timestamp < ? -- $timestamp
                   AND ses_session_id <> ? -- $this->getValue(\'ses_session_id\')';
        $this->db->queryPrepared($sql, array($timestamp, $this->getValue('ses_session_id')));
    }
According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization."