Woocommerce – Filter Variable Products by Variation Attributes and Variations Regular Price

So, I finally figured out the answer… This may help someone in future.

Here is the query that will first filter variable products for attribute Quantity which has term id 75 and then it will further filter result for variations which has price 500 set.

            $query = array(
                'post_status' => 'publish',
                'post_type' => array('product', 'product_variation'),
                'posts_per_page' => 10,
                'tax_query' => array(
                    'relation' => 'AND',
                    array(
                    'taxonomy' => 'pa_quantity',
                    'field' => 'term_id',
                    'terms' => '75',
                    ),
                ),
                'meta_key' => '_price',
                'meta_value' => 500,
            );

            $wc_query = new WP_Query($query);