How to unset an array by null key in php

Before:

$my_array = Array ( [TRUE] => 1 [FALSE] => 2 [] => 0 ) 

I wanna remove the array if the key[] is null.

My concept :

if ($my_array.key is null) {
    unset($my_array.key)
}

Hope the array becomes:

$my_array = Array ( [TRUE] => 1 [FALSE] => 2)