There is only one file type that uses the .KYS extension:
Adobe Photoshop Keyboard Shortcuts File
A KYS file contains keyboard shortcuts created by Photoshop, a professional graphics editing program. It saves custom key combinations used to trigger menu options and other commands. KYS files allow shortcuts to be restored between installations of Photoshop.
KYS files can be created and loaded from Photoshop's Keboard Shortcuts & Menus window, which can be opened by choosingfrom the application menu.
Examples of common Photoshop keyboard shortcuts include Cmd-Shift-N for creating a new layer, and Cmd-Opt-I, which opens the resizing window. Functions that that don't have default shortcuts, such as the Brightness/Contrast window, can have their own shortcuts applied and saved to a KYS file. Default shortcuts may also be overwritten.
NOTE: KYS files are also used by Adobe Illustrator.
Updated: September 4, 2018