add_action('rest_api_init', function () {
    register_rest_route('custom/v1', '/server-time', array(
        'methods' => 'GET',
        'callback' => function() {
            $server_time = current_time('mysql');
            $timestamp = time();
            return [
                'server_time' => $server_time,
                'timestamp' => $timestamp
            ];
        }
    ));
});