nginx with php-fpm location settings

Many of the guides for setting up Wordpress (or similar applications) on nginx with php-fpm use a configuration that in part looks something like this:

 location    ~ [^/]\.php(/|$) {
              fastcgi_split_path_info ^(.+?\.php)(/.*)$;
              if (!-f $document_root$fastcgi_script_name) {
                #some guides suggest try_files $uri =404; instead
                return 404;
              }
              fastcgi_pass php;
              fastcgi_index index.php;
              include fastcgi_params;
  }

  #Route anything not otherwise matched
  location / {
      try_files $uri $uri/ /index.php$is_args$args;
  }

With this configuration if the requested URI /someuri isn't an actual location it'll get routed to index.php and from there to the backend.

The 404 part is there to prevent unauthorized code execution, so if the requested URI is /somefile.php which doesn't exist then a simple nginx 404 is generated.

What would be a better way to configure this (& remain 'secure') so that a request for a nonexistant php file also get passed to the backend via index.php?