Unlike the other lock doors (or lock block that changes next map16), this door wouldn't use/consume the key on contact, instead, it requires mario to hold the key, stand in front of the door on the ground and press up to enter, much like smb2.
It also check mario's x position compared with the door if he's centered enough (exactly like how smw won't let him from the very edge).
-If you're using sa-1 patch (and after you converted the ram addresses), it may not work. This is because the block still uses a 12-slot sprite loop, and sa-1 makes it so the game handles 22 slots instead of 12. To fix that, make sure that you manually change the loop to use 22 (hint: it's a loop counter) slots.
Rendered redundant (i.e. functionally identical) by this door pack (which can be locked in the same way as these doors).