title: .htaccess only allow if key is correct, and in URL
body: <p>My website has some PDF files stored in the web folders.</p>
  <p>I do not want to show them of to the whole internet.
  I want the PDF's only to be shown when they have a specific and correct key in the url like:
  <a href="https://example.com/folder/test.pdf?authkey=123" rel="nofollow noreferrer">https://example.com/folder/test.pdf?authkey=123</a> or (Whatever key that is assigend in the MySQL db, each file has it's own specific key)</p>
  <p>A PHP script declares the authkey to the file. And deletes the authkey after x hours.</p>
  <p>How can this be achieved in .HTACCESS?</p>
  <p>Other suggestions are welcome to!</p>