Redirecting folder.with variables in url's

[siteseo]

I'm trying to figure out how to redirect an entire folder (now defunct) to my home page. The tricky part is, some of the files in that folder are indexed with variables as part of the URL's. Is there a way to redirect calls for ANYTHING within the folder, to the home page? Here's what I've tried with no success, along with several variations:

RewriteRule ^old-folder/(.*)$ [domain.com...] [R=301,L]

Here's a sample URL that I'm trying to redirect:
www.example.com/old-folder/file.php?prod=1556

[extras]

The QUERY_STRING (what you called 'variable') will follow unchanged.
But you need to include subdirectory and/or file name.

RewriteRule ^old-folder/(.*)$ [domain.com...] [R=301,L]