How to Filter in a PHP Array? [closed]

I have a Array of which I need to filter, I am using array_filter the following way:

<?php

$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];

var_dump(array_filter($arr, function($v, $k) {
    return $k == 'b' || $v == 4;
  }, ARRAY_FILTER_USE_BOTH));
?>

Effectively it works and returns the filtered result that is the index b and index d , but to me what I would like it to be filtered more precisely if the index b is Value 2 .

Try as follows:

<?php

    $arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];

    var_dump(array_filter($arr, function($v, $k) {
        return $k == 'b' && $v == 4;
      }, ARRAY_FILTER_USE_BOTH));
    ?>

But it does not return any value to me.