Select Metaboxs by Attribute Flag

I am attempting to automatically create filters on the front end based on some back-end metaboxes. facet-wp is not being used as it's too much overhead for this simple use.

The fields to be used as filters are flagged as as such using is_filter during the field creation like so:

'fields' => array(
    array(
        'name'  => __('Gender', 'text-domain'),
        'desc'  => '',
        'id'    => 'user_gender',
        'type'  => 'select',
        'options'    => array(
                        'Male'      => __('Male', 'text-domain'),
                        'Female'    => __('Female', 'text-domain'),
                        'Diverse'   => __('Diverse', 'text-domain'),
                    ),
        'attributes' => array(
                        'required'  => true,
                        'mod_lock'  => true,
                        'is_filter' => true,
                    ),
   ),
)

Is there a recommended way of selecting all fields that have is_filter set?
This following is working, but maybe there is a better method?

$meta_box_objects = rwmb_get_registry( 'meta-box' )->all();
foreach ( $meta_box_objects as $meta_box_object ) {
    $fields = $meta_box_object->fields;
    foreach($fields as $field){
        if(!empty($field['attributes']['is_filter'])){
            //filter field found
            $content .= $field['id'].'<br/>';
        }
    }
}

rwmb_get_registry is not very well documented, so maybe there is a more efficient method?