- var_dump: documentation ( source)
- in_array: documentation ( source)
<?php
$key = 12345;
$email = "somto@gmail.com";
$keyArr = array(12345 => array("somto@gmail.com", "james@yahoo.com",), 54321 => array("munz@gmail.com",));
$errors = [];
if (!array_key_exists($key, $keyArr) || !in_array($email, $keyArr[$key])) {
$errors['key'] = "Invalid email or key!";
}
var_dump($errors);