I don't neccesarily think it's a bad idea, but be aware of a few things:
1) We do have several keys, plus qntm's proposal. Be sure you don't inadvertantly mimic one of them
2) Ever wonder why it is that anytime a character in a movie describes a plan, it fails? It's because, if everything went according to plan, that plan becomes a spoiler and the audience has no reason to watch it unfold. That's what you have here: a spoiler. After reading "two dimenional key" I instantly knew pretty much everything about the object, and would have no reason to keep reading. For SCPs to be engaging, they usually need some kind of hook, a part of the SCP that really grabs the audience's attention; something truly terrifying, or something that really makes you stop and think. This one doesn't really have a hook as you described it, it's more of a "This is a funny looking key with an unknown origin." Pretty much everything in the Foundation has an unknown origin, so you need more than that.
Now, that said, do not force it. One of the biggest mistakes I see new members make is trying to force an idea to be scary/interesting, or trying to shoehorn it into being euclid/keter when it's actually safe. I can't speak for other writers, but in my experience some idea just don't lend themself to an engaging hook; I've had ideas that, while I loved the concept, I scrapped them because I simply couldn't find a good way to make the reader care.
3) Technobabble can be engaging, but be careful with it; it is almost never enough to sustain an SCP on its own. SCPs need substance beyond the babble, so just be aware of that when you're writing.
So, there's my two cents. Take it for what it's worth, which probably isn't much. Good luck!