Use Yoast Filter to modify value of wp_head output?

I want to modify my wp_head. I am using the Yoast plugin I want to add a new custom meta tag after the description meta tag. I try this code for add keyword tag but it’s not shown after the description tag its shown in a lower position this code

    /*Display custom meta keywords or the post excerpt */
function add_custom_meta_key(){

#Single Page Meta Description
if( is_single() ){
    $key = get_post_meta( get_the_id(), 'keywords', true);
    if( ! empty( $key )  ){
        $meta_key = esc_html($key);
        echo '<meta name="keywords" content="' . $meta_key . '" />';
    }
}}
add_action( 'wpseo_head', 'add_custom_meta_key', 2 );