You can try something like this:
<?php
$list = array();
$list[7362][0]['value'] = 'apple';
$list[7362][1]['value'] = 'orange';
$list[9215][0]['value'] = 'lemon';
foreach ($list as $keynum=>$keyarr) {
    foreach ($keyarr as $key=>$index) {
        if (array_search('orange', $index) !== false) {
            echo "orange found in $key >> $keynum";
        }   
    }   
}
?>
You can choose to just echo out echo $keynum; for your purpose.
Loop through the arrays and find out where you find orange.
You can refactor that a bit into a function like this:
<?php
function getKeys($list, $text) {
    foreach ($list as $keynum=>$keyarr) { 
        foreach ($keyarr as $key=>$index) { 
            if (array_search($text, $index) !== false) {
                return "$text found in $key >> $keynum";
            }
        }
    }
    return "not found";
}
$list = array();
$list[7362][0]['value'] = 'apple';
$list[7362][1]['value'] = 'orange';
$list[9215][0]['value'] = 'lemon';
echo getKeys($list, 'lemon');
?>
echo getKeys($list, 'lemon'); will give you lemon found in 0 >> 9215.
echo getKeys($list, 'orange'); will give you orange found in 1 >> 7362.
echo getKeys($list, 'apple'); will give you apple found in 0 >> 7362.