Migrated users without last login date has "1970-01-01 01:00:00" as this value

How to reproduce:
1. Find somehow user, who never logged forum after registration
2. Open its profile

AR:
"01 Jan 1970 04:00" is displayed as last login

ER:
Last login is empty

DB query:
Select *
from USERS
where last_login like '1970%'

Note: Also 100% of migrated users has ENABLED = 1,although the new user has this field = 0