$method1 = strtotime('now') + 3600; // Add 3600 seconds to numeric timestamp
$method2 = strtotime('1 hour'); // Get the time in one hour from strtotime()
echo 'Method n.1: ' . date('Y-m-d H:i:s', $method1);
echo '<br>';
echo 'Method n.2: ' . date('Y-m-d H:i:s', $method2);