Does not come from World of Warcraft or Korean. Back when gaming just started going multiplayer and worldwide. The Dutch people were a big group of users. The word 'Kek' origins from the 1974's when it used to mean 'Modern', 'Fancy', 'Nice' in
Dutch. Often combined with '
top' as in 'top kek', also often used in Dutch.
Through the world of gaming,
reddit, 4chan it grew to a larger audience just like the Dutch word 'lol' which means fun.