Same issue here!
I found out that the API is not present in all SuprNova Pools (under Account tab).
BTCZ is also missing the API-Key for me, but the API is present @BYG pool page (Account Tab).
Hope that the API is shown soon again ...
TIP: You can use the API KEY from another pool (under you login), but in my case I do not get all info, but I do See the amount of workers that are online and the 'confirmed' and 'unconfirmed' amount of coinz.