expiry stops working after process is live for a few years

[romange]

We use base + offset computation for expiry, where offset is 32bit value that could hold milliseconds period. In practice we are limited to ~36 hours before the offset overflows. We need to implement a per-hour process that updates the offsets in the expire table.

[romange]

Temporarily as a workaround made expiry type as 64bit.