protected function cleanup($queue)
    {
        $sql = implode(" ", [
            sprintf(
                'SELECT id FROM %s',
                $this->quoteIdentifier($this->config('table'))
            ),
            sprintf('WHERE %s = ?', $this->quoteIdentifier('queue')),
            'AND expires_at < ?'
        ]);

        $datetime = new DateTime;
        $dtFormatted = $datetime->format('Y-m-d H:i:s');

        try {
            $sth = $this->connection()->prepare($sql);
            $sth->bindParam(1, $queue, PDO::PARAM_STR);
            $sth->bindParam(2, $dtFormatted, PDO::PARAM_STR);

            $sth->execute();
            $result = $sth->fetch(PDO::FETCH_ASSOC);

            if (!empty($result)) {
                $this->reject([
                    'id' => $result['id'],
                    'queue' => $queue
                ]);
            }
        } catch (PDOException $e) {
            $this->logger()->error($e->getMessage());
        }
    }