检查是否存在WordPress密码保护cookie

With WordPress, if you're using password protected pages, when the user uses a successful password, a cookie is generated looking something like this:

wp-postpass_299da1fd9cb967a93782c5397fa3a35e

Is there anyway in PHP to do a check if this cookie exists?

Even just check if a cookie exists which starts with wp-postpass_?

Contents of $_COOKIE when I run var_dump($_COOKIE):

array(9) {
    ["wordpress_test_cookie"] => string(15)
    "WP Cookie check" 
    ["wp-postpass_299da1fd9cb967a93782c5397fa3a35e"] => string(34)
    "$P$BXtsZ0i1qom3bqiFk4b9GeG8l9dFVG." 
}

if(isset($_COOKIE)){
    foreach($_COOKIE as $key=>$val){
        if(strpos($key,'wp-postpass_') === false) {
        //not found
        }else{
        //found
        }
    }
}

I found a more elegant solution than the accepted answer on WordPress Developer Docs to see if the cookie exists:

if ( isset( $_COOKIE['wp-postpass_' . COOKIEHASH] ) ) {
     //custom code 
}

Likewise, if you want to check if the cookie doesn't exist:

if ( ! isset( $_COOKIE[ 'wp-postpass_' . COOKIEHASH ] ) ) {
    //custom code
}

This code is useful for pages that might not have password protection because they are an archive page or what not, but the content it contains may be protected (such as a post).