Possible to avoid cost increase in move to GCP MySQL Second Generation?

I was using pay-per-use with MySQL first generation. It was a website with all I was using pay-per-use with MySQL first generation. It’s for a website with all pages cached in memcached and only evicted from cache when I update content. Writes to SQL can also occur if somebody register for newsletter or similar (happens ~10 times/month). I was getting away for free with the pay-per-use model, but that model is not available in the second generation.

As far as I can understand, there is no way to get below $ 7 per month now with the new model. Is that correctly understood?

Or is there an API where I can turn on/off the SQL instance when I receive a registration or update content? It feels strange to pay so much for a service I use for less than a second 10-100 times per month.