There is only one file type that uses the .LIGHTKEYPROJ extension:
A LIGHTKEYPROJ file contains a project created by Lightkey, a professional program used to configure and control DMX-compatible lighting fixtures for various types of venues. It stores project information, which includes light fixtures and light shows configured for a lighting display. LIGHTKEYPROJ files are working files, which means they can be modified, saved, closed, then reopened for further editing.
Updated: October 26, 2019