Cross platform UUID/API key

<?php

class APIKey {

    public static function createKey() {
        $key = null;

        do {
            sprintf('%04X%04X%04X%04X%04X%04X%04X%04X', mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(16384, 20479), mt_rand(32768, 49151), mt_rand(0, 65535), mt_rand(0, 65535), mt_rand(0, 65535));
        } while (self::validateKey($key));
    }

    public static function validateKey($key) {
        $stmt = Database::$db->prepare("SELECT COUNT(*) FROM APIKEY WHERE uuid = ?");
        $stmt->execute(array($key));
        return ($stmt->fetch()[0] > 0);
    }

}

$key = APIKey::createKey();