Prison Of Hope Locked Doors

I can't remember if this is dependent on world status but there is a door that takes you to a set of stairs that is to the right of the door that takes you to the cutscene and the ballista statue. At the top of those stairs is a locked cell door. I just rant all through the area twice. I haven't killed Fool's Idol yet. I did kill the invader in front of her doors. So I think I have all the keys but I can't open that door.

Is that door available when the world is white or black or did I miss the key somewhere?