好的，我已经创建了自己的函数来检查真/假条件。这似乎奏效了。你觉得怎么样？

function is_this_afield() {
global $wp_query;
$postid = $wp_query->post->ID;  
if (get_post_meta($postid, \'flatme\', true)) {
return true;
} elseif(is_page_template(\'template-flat.php\')) {
return true;
}else {
return false;
} 
wp_reset_postdata(); 
}

function flatsome_scripts() 
{
if(is_this_afield()) {
wp_enqueue_style( \'flatsome-icons\', get_template_directory_uri() .\'/flatme/css/fonts.css\', array(), \'2.1\', \'all\' );
}
}

add_action( \'wp_enqueue_scripts\', \'flatsome_scripts\' );

尝试custom field parameters for WP_Query

$cf_query = new WP_Query( array (
    \'order\' => \'DESC\',
    \'meta_query\' => array(
        array( \'key\' = > \'_flatme_key\')
    )
)); 

或WP_Meta_Query