I’d like to retrieve the post_id from wp_post_meta with a unique meta_key and meta_value. I’ve tried WP_Query but no values are returned and I’m unable to retrieve the post_id‘

$post_query = new WP_Query( array(
    'meta_key' => 'key',
    'meta_value' => 'value',
    'fields' => 'ids',
) );

$post_ids = wp_list_pluck( $post_query->posts, 'ID' );

return $post_ids;

A similar post on Stackoverflow suggests that the only way is using a SQL query which differs to the suggestion from Sally CJ.

Using a SQL query returns the post_id. If possible, I’d like to use WP_Query or a native function if there’s one.