Magento Nginx: Never rewrite for existing files, directories and links

Question

I install my Magento CE 1.8.1 on Nginx server.

My nginx conf file is like this: Configuring nginx for Magento

I created a subfolder in Magento root folder, then put in it some php files. I tried to execute those files by visiting urls (http://example.com/magento/subfolder/myfile.php) but it displays Magento 404 page. That means it was forced to rewrite by conf.

I looked into Magento default .htaccess file and found these lines:

############################################
## never rewrite for existing files, directories and links

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l

How to convert this into nginx conf and make existing files executable?