How to find your action in admin-ajax.php file?

I am using woo commerce plugin for my eCommerce website. There are some order listed on my dashboard. When i change status of an order from processing to completed we click on button. Here is my action goes

if ( in_array( $the_order->post_status, array('wc-pending', 'wc-on-hold', 'wc-processing') ) )
                            $actions['complete'] = array(
                                'url' => wp_nonce_url( admin_url( 'admin-ajax.php?action=upen-mark-order-complete&order_id=' . $the_order->id ), 'upen-mark-order-complete' ),
                                'name' => __( 'Dispatched', 'dokan' ),
                                'action' => "complete",
                                'icon' => '<i class="fa fa-truck">&nbsp;</i>'
                            );

but when i am looking into admin-ajax.php file there is no order_id getting. I am confused that where these attributes are we getting to change order status like action, order id etc.

via Chebli Mohamed