A "KSP DLC unlocker.exe" that is 150KB? That cannot possibly contain a working crack. But it can contain a downloader for much nastier things.
Using a DLC unlocker is a form of piracy. It denies the developers at Squad and Private Division revenue for their work, which can affect the future development of the series. Alternatives to Unlockers ksp dlc unlocker
The KSP community is generally supportive of modding but has a complicated view on piracy and DLC unlocking. A "KSP DLC unlocker