PHP Decode

<?php  
include('connect.php');  
if($_GET['key'] == null || $_GET['pc'] == null){die();} 
$mysqli = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);  
$db = mysql_connect(DB_HOST, DB_USER, DB_PASS);  
mysql_select_db(DB_NAME, $db);  
$mysqli->query("SET CHARACTER 'utf8'");  
$u_key = $_GET['key'];  
$u_hwid = $_GET['pc'];  
$db_ex = $mysqli->query("SELECT * FROM `BlocadePrivat` WHERE (`key_user`='$u_key')");  
$row_ex = $db_ex->fetch_array();  
if($row_ex['pc'] == null){$mysqli->query("UPDATE `BlocadePrivat` SET `pc`='".$u_hwid."' WHERE (`key_user`='$u_key')");}  
else{if($row_ex['pc'] != $u_hwid){die("ERROR");}}  
if(strtotime($row_ex['data']) <= strtotime(date('d.m.Y'))){die("ERROR");}  
else{echo'OK DATA{'.$row_ex['data'].'}';} 
?>