How to show the post which checkbox is not selected

I have custom post type and created one custom field checkbox called is_featured.
I have to show the post which is the checkbox is selected so I have used the below code and it’s working

function isFeatured($atts){
global $post;
 $args =array(
      'post_type' => 'postname',
      'post_status' => 'publish',
      'posts_per_page' => 30,
      'meta_key' => 'isfeatured',
      'meta_value' => 1,
      'order'      => 'DESC',
      'orderby' => 'post_date',
    );

$related = new WP_Query($args);
if( $related->have_posts() ) { 
$data = '<ul>';
 while( $related->have_posts() ) { 
        $related->the_post(); 
        $data.= '<li></li>';
                }
     $data .='</ul>';
    return $data;
    wp_reset_postdata();
}

}
add_shortcode( 'is-featured', 'isFeatured');

Now, My issue is, How to show the post which checkbox is not selected?