If I have a sprite at a battlefield with a hidden Consult the Past. When it becomes my turn, am I able to react and resolve Consult the Past or would it be discarded?

Yes, you can absolutely react to the Sprite token's temporary trigger by flipping your hidden Consult the Past before the token is removed.

According to the rules and established FAQs for Riftbound:

1. Temporary Trigger: At the beginning of your turn, the Sprite token's temporary trigger goes on the chain.
2. Reaction Window: Because this trigger is on the chain, you have a window to play reactions.
3. Resolution: You can flip your hidden Consult the Past in response to this trigger. Because the chain resolves in Last-In, First-Out (LIFO) order, your Consult the Past will resolve first, allowing you to draw your cards before the Sprite token is removed from the battlefield.

The token is not removed automatically in a way that discards your hidden card; you have the priority to act before that happens.