Query pages for use of a flexible content layout

I have a site that originally used a repeater field for selecting layout options. I now use the flexible content field. I need to be able to query the site for pages that use “featured-resources” as a row layout.

In the past, I could query sub-fields of the repeater field using this within a custom template:

function query_subfields( $where ) {
    $where = str_replace("meta_key = 'mods_$", "meta_key LIKE 'mods_%", $where);
    return $where;
} 
add_filter('posts_where', 'query_subfields');

<?php
$args = array(
'posts_per_page'    => -1,
'post_type'     => 'page',
'meta_query'    => array( array(
'key'       => 'mods_$_choose_module',  // WHAT REPLACES choose_module ??
'value'     => 'Featured Resources',
'compare'   => '='
))
);

$the_query = new WP_Query( $args );
?>

<?php if( $the_query->have_posts() ): ?>
<ul>

<?php while( $the_query->have_posts() ) : $the_query->the_post(); ?>
<li><a href="https://wordpress.stackexchange.com/questions/332605/<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
<?php endwhile; ?>

</ul>

<?php else : ?>

<p>No matches.</p>

<?php endif; ?>

<?php wp_reset_query(); ?>

Now that I’m using flexible content, I don’t know how to define the 2nd part of the key. Content templates use get_row_layout(); to add field contents to pages, but this is not a key. From what I’ve read, I believe the key for these subfields is randomly generated. How do I allow for this, so that I’m able to generate a list of pages using this row layout?

I posted this on the ACF support forum as well and got great feedback: https://support.advancedcustomfields.com/forums/topic/query-pages-for-use-of-a-flexible-content-layout/

With a bit of tweaking, it worked. Here’s what I ended up with:

<?php
    $flex_content_name="flexible_content";  // < update with applicable field name
    $layout_name="featured-resources";  // < update with applicable subfield name
    $args = array(
        'posts_per_page'    => -1,
        'post_type'     => 'page',
        'meta_query'    => array(
            array(
                'key'       => $flex_content_name,
                'value'     => '"'.$layout_name.'"',
                'compare'   => 'LIKE'
            )
        )
    );

    $the_query = new WP_Query( $args );
?>

<?php if( $the_query->have_posts() ): ?>

    <ul>
    <?php while( $the_query->have_posts() ) : $the_query->the_post(); ?>
        <li>
            <a href="https://wordpress.stackexchange.com/questions/332605/<?php the_permalink(); ?>">
                <?php the_title(); ?>
            </a>
        </li>
    <?php endwhile; ?>
    </ul>

<?php else : ?>
    <p>No matches.</p>
<?php endif; ?>

<?php wp_reset_query(); ?>