The key glitch is a glitch used to skip collecting keys from dungeons by using keys from a previous file. In order to get it to work you need to play on a file up until the first dungeon. In the dungeon go past the first key door and then collect the two keys later in the dungeon. At this point you want to return to the entrance of the dungeon and use the save orb. This file now has 2 keys saved to it. Once you deleted this file and start a new game on the same file the new game will have 2 keys. Repeat this process until you have enough keys to complete the any% route.