This is why Planète-Casio started hosting other people's programs a while ago. Although in the English community this is generally discouraged without the author's permission, this practice has saved FxLock from no longer existing and as a result, you can still find a backup copy available at http://www.planet-casio.com/Fr/programmes/voir_un_programme_casio.php?showid=2425&page=2

I'm unsure if it's the latest version, though. Also, it might not work on SH4 calculator models from 2011 or so and make sure you don't forget your password.