Grimrock

Door:setOpenedBy(key)
Sets the name of the item which can be used to unlock this door. Works only with doors with built-in locks.

How i can use the key ID instead key name?

As far as I know you can't. But you can easily set up a new item in your dungeon's items.lua, so it's not a big deal.

Okay, thank you, Komag.

UPD: What means the gfxIndex line in items.lua?

It's the number of the little icon used