WP Query with meta queries

You have to use "orderby" => "meta_value_num" and set a "meta_query" at the same time. Then choose the "meta_key" you want to order by.

Try:

$query = new WP_Query(
    array(
        'post_type'      => 'some_cpt',
        'posts_per_page' => - 1,
        'meta_query'     => array(
            array(
                'key'     => 'active',
                'value'   => '1',
                'compare' => '=',
            )
        ),
        'meta_key'       => 'ranking',
        'orderby'        => 'meta_value_num',
        'order'          => 'ASC',
    )
);