Array sorting by custom field date

Hi
Have got sttuck – i want to order the array by a date field called ‘date_start’ but how do I include a meta_key for this if I already have a meta_key?

‘
<?php $currentshowid = get_the_ID(); ?>
<?php
$today = date(‘Y-m-d’);
$args = array(
‘meta_key’ => ‘show_id’,
‘meta_value’ => $currentshowid,
‘orderby’ => ‘meta_value_num’,
‘order’ => ASC,
‘meta_query’ =>array(
‘relation’ => ‘AND’,
array(
‘relation’ => ‘AND’,
‘key’ => ‘date_end’,
‘value’ => $today,
‘compare’ => ‘>=’,
),
),
); ‘