That's probably cheaper in size than the one proposed by hosseinimr93, but quite easy to mess with it during the beginning. There is no standard manner to construct a transaction spending in a P2SH as the one you've provided, so you'll have to construct it individually, which isn't recommended unless you really know what you're doing.
Yeah, agreed. Should've caveat that it is probably not too good to mess with ScriptSig if you're inexperienced. Good to test with regtest before trying it out on mainnet with small amounts of BTC though. P2WSH/P2SH is pretty versatile in the sense that you can create redeem script with a bunch of conditions and customize it to your use case.
I don't foresee these kinds of scenarios to be prevalent enough to warrant a standard though. Going by OP's question, that is the only way this can be achieved if you're mapping 1 key -> 1 entity.