How to curl `ink!` contract storage?

Question

I'm trying to use curl to query an ink contract's storage using the RPC of substrate. I've looked at the below question

How do I call the RPC method `contractInfoOf` using curl?

but it does not specify how exactly to do this. I've got as far as

curl -H 'Content-Type: application/json' --data '{ "jsonrpc":"2.0", "method":"state_getKeys", "id":2 }' localhost:9944

but this yields {"jsonrpc":"2.0","error":{"code":-32602,"message":"No more params"},"id":2}. I know I need to supply further parameters to specify the contract address, but it is unclear how to do that.

Here's the contract storage in ink

    #[derive(Default)]
    #[ink(storage)]
    pub struct MyContract<KEY: StorageKey = ManualKey<0xABCDEF01>> {
        a: u8,
        b: u8,
        c: u8,
    }

I've tried giving the contract storage a set key using curl -H 'Content-Type: application/json' --data '{ "jsonrpc":"2.0", "method":"state_getKeys", "id":2, "key":"0xABCDEF01" }' localhost:9944 with no avail, same error message.

The contract's address is 5F4N6ctYoDk1yqD4bSRh6eFottkfPWrxSPAcpq2m78sMoarJ in my substrate-contracts-node instance, I assume I need that somewhere in the command to specify the contract.

Any ideas?