按开始日期查询，然后按Wordpress中的开始时间查询

I am trying to query the database and ordering the result by the date and then by time. But with the query below it only orders by the start time. When I remove the start time it orders the result by date.

So far I have tried changing the order and multiple solutions throughout the web but nothing works.

$args = array(
                        'numberposts'   => -1,
                        'post_type'     => 'reservation',
                        'cat' => $categorie,
                        'meta_key' => 'start_time',

                        'orderby'  => array( 'start_date' => 'ASC', 'meta_value_num' => 'ASC' ),
                        'posts_per_page'  => 10,
                        'meta_query'    => array(
                            'relation'      => 'AND',
                            array(
                                'key'       => 'start_date',
                                'compare'   => '>=',
                                'value'     => $date,
                            ),
                            array(
                                'key'       => 'reservation_status',
                                'compare'   => '<',
                                'value'     => 3,
                            )
                        )
                    );
                    // query
                    $the_query = new WP_Query( $args );

Please help.

Thanks

How about something like this:

order => 'start_date start_time',
orderby => 'ASC',