Write a smart contract

A tenant wants to rent an apartment from a landlord. To maximize efficiency, I want to use a smart contract for this. The tenant would transfer the deposit to a third address (escrow account), and the landlord transfers a non-fungible token to this address. Then, on an agreed upon date, the token is transferred to the tenant and the deposit to the landlord. This token would act as a key, used to open a smartlock on the apartments door, or opening a safe with the physical key inside. This would not need to be coded! I only need the smart contract, nothing else. This is just a PROOF OF CONCEPT, it doesn't need to work! Therefore, the token doesn't need to exist, and the smart contract will not be deployed. It's only meant to show what Solidity and smart contracts can do.