Search multidimensional array for value

Kirby 3 Questions 🤔
#1

Hi. I have this array structure:

Array
(
    [0] => Array
        (
            [variations] => Array
                (
                    [0] => Array
                        (
                            [option] => Πέτρα
                            [variation] => Διαμάντι
                            [price] => 100
                            [variation_available] => false
                        )

                    [1] => Array
                        (
                            [option] => Πέτρα
                            [variation] => Ζαφείρι
                            [price] => 50
                            [variation_available] => false
                        )

                )

        )

    [1] => Array
        (
            [variations] => Array
                (
                    [0] => Array
                        (
                            [option] => Μέγεθος
                            [variation] => Μεγάλο
                            [price] => 
                            [variation_available] => false
                        )

                    [1] => Array
                        (
                            [option] => Μέγεθος
                            [variation] => Μικρό
                            [price] => 
                            [variation_available] => false
                        )

                )

        )

)

How can I check if any sub-array contains the key [variation_available] with the value of false?

#2

I think array_filter would probably the best option: https://www.php.net/manual/en/function.array-filter.php