Find MySQL InnoDB index corruption
On 26 October 2014, following another change in the law, the clocks in most of the country were moved back one hour, but summer Daylight Time was not reintroduced; Moscow Time returned to UTC+03:00 permanently.


-- https://en.wikipedia.org/wiki/Time_in_Russia

It sounds like your system (OS and/or MySQL) need an update to the TZ tables.

Down with DST!