You cannot get a balance with a view key alone. All you can do with a view key is view incoming transactions - not get a wallet balance. To determine a wallet balance you also need a way to know what is spent. With a view-only wallet, you can import key images which will enable you to view a balance. Thus, you would first have to create a view-only wallet ...
How do I view only these transactions that were sent to this subaddress?
[wallet]: help incoming_transfers
incoming_transfers [available|unavailable] [verbose] [uses] [index=<N1>[,<N2>[,...]]]
Show the incoming transfers, all or filtered by availability and address index.
The command to view the properties is the set command. You can access it like this:
./monero-wallet-cli --daemon-host XMR_NODE --wallet-file WALLET_FILE \
--password 'XXXXX' set
To set a property, you just run the following:
set ask-password 0