// Set custom attribute name and value to search for

$attribute_name  = 'color';

$attribute_value = 'green';

​

$serialized_value = serialize( 'name' ) . serialize( $attribute_name ) . serialize( 'value' ) . serialize( $attribute_value ); // extended version: $serialized_value = serialize( $attribute_name ) . 'a:6:{' . serialize( 'name' ) . serialize( $attribute_name ) . serialize( 'value' ) . serialize( $attribute_value ) . serialize( 'position' );

$args = array(

    'post_type'      => 'product',

    'post_status'    => 'any',

    'posts_per_page' => -1,

    'orderby'        => 'title',

    'order'          => 'ASC',

    'meta_query' => array(

        array(

            'key'     => '_product_attributes',

            'value'   => $serialized_value,

            'compare' => 'LIKE',

        ),

    ),

);

$loop = new WP_Query( $args );

while ( $loop->have_posts() ) {

    $loop->the_post();

    // do stuff here... e.g. get_the_ID()

}

wp_reset_postdata();