My gut feeling would say that you're talking about a bitcoin core wallet, since the wallet's name is wallet.dat, it's a file from 2015 AND you're talking about pywallet.

You don't need to unlock your wallet to see the balance, however, there are 3 ways to see the balance:
1) use core to load the wallet.dat and wait untill core syncs... This will probably take several days, maybe even weeks
2) use pywallet to export the private keys and import those in an SPV wallet like electrum
3) use core to load the wallet.dat, use the console to list all addresses, import those addresses into an SPV wallet to create a watch-only wallet

Why don't you want to use pywallet? Is there a reason, or is it just because you don't want to invest time in setting everything up? Pywallet would be by far the fastest way to be able to spend those funds... Option 1 will take ages and option 3 is a watch-only wallet...

EDIT: i just realised you probably don't want to use pywallet because you forgot your password... Maybe this tool will help?
https://github.com/gurnec/btcrecover