There is only one file type that uses the .KLC extension:
Keyboard Layout Creator Source File
A KLC file contains a keyboard configuration created by Microsoft Keyboard Layout Creator (MSKLC), a program used to create or modify keyboard layouts. It stores a layout of a keyboard and the functions associated with the keys. KLC files may include colors for assignable keys, dead keys, and unassignable keys.
|Microsoft Keyboard Layout Creator||Free|
Updated: December 13, 2019