Here's a nitpick: It's key/value store, not key-value store.
A key-value store would only store "key values."
I don't know of any rule of English grammar that would lead to this interpretation. If you do, you should immediately write to the maintainers of these websites:
https://redis.com/nosql/key-value-databases/
https://www.mongodb.com/databases/key-value-database
https://aws.amazon.com/nosql/key-value/
https://etcd.io/docs/v3.4/learning/why/
https://riak.com/products/riak-kv/