WooCommerce – Multiple meta query not working

meta_query format and orderby format should be as follows:

$args = array(
    'post_type'     => 'product',
    'post_status'   => 'publish',
    'posts_per_page'=> 10,
    'orderby'       => 'total_sales',
    'order'         => 'DESC',
    'meta_query'    => array(
        'relation'  => 'OR',
        array(
            'key'       => '_featured',
            'value'     => 'yes',
            'compare'   => '='
        ),
        array(
            'key'       => 'total_sales',
            'value'     => '10',
            'compare'   => '>='
        )
    )
);
$query = new WP_Query( $args );

Instead of meta_key and meta_value use key and value with compare as mentioned. You can see related documentation of WP_Meta_Query which also works with WP_Query.