Crack Salt

[li0nsar3c00l]

I do have a certain plaintext, the hash and know the encryption algorithm, which is hmac sha256.
is it possible to brute the right salt? i know the salt is a 64char alphanumeric string.

as i'm completly new to hashcat, could anyone help me with the proper parameters?

thanks in advanced

[atom]

It's possible for hmac-sha256, but only up to length 55