Under normal circumstances, “accessing” qa-config.php does nothing, you will just see a blank page. However it could be an issue in rare cases if your server becomes misconfigured and serves the code.
The simplest solution is to move it outside the web root. For example if the root of your website is ‘/var/www/website/public_html’ then put the file in the ‘website’ directory.
Then make a new qa-config.php file in ‘public_html’ that includes the other one, e.g.
More info on security in the docs here.