How to purposefully exclusively lock a file?

Question

I want to hold an exclusive lock on a file so it cannot be read or written by anything else. Is there a simple Windows tool or command to do this?

I suppose the tool or utility would implement the LockFileEx Windows Function.

Note: I've tried text editors like Notepad and Notepad++ on a text file but they don't hold an exclusive lock on it.

Answer 1

Open it with MS-Excel... this app locks a file while open.

Answer 2

Try Easy File Locker (freeware).