> I've done this many times in AWS leveraging dynamodb.

Exactly. I think nosql offerings from any cloud provider already supports both TTL and conditional requests out-of-the-box, and the performance of basic key-value CRUD operations is often <10ms.

I've seem some benchmarks advertise memory cache services as having latencies around 1ms. Yeah, this would mean the latency of a database is 10 times higher. But relative numbers matter nothing. What matters is absolute numbers, as they are the ones that drive tradeoff analysis. Does a feature afford an extra 10ms in latency, and is that performance improvement worth paying a premium?