The Korean retail version only started a little more than a week ago (on 1/18). So that means they got to level 60, ran the insane prereq quests to get a key to her lair, and beat her in 10 days.
There's like 12 quests before you can get a key to the lair - one of them involves running an instance (in a 5 man group) to get an item you need to make a key. The instance only drops 1 of the item per group, so you have to run it 40 times to get enough for a while raid party. I've heard the instance takes 2-3 hours, so even at the minimum, that's 80 hours right there.
They HAD to be botting and/or exploiting low-hp mobs (there are unfinished areas that are difficult to get to but have Elite mobs with 10hp that give regular XP for their level).
Edit: Ohh - apparently they didn't do a character wipe from beta-->retail for Korea, so they could have been at the cap when it launched