Time fields are stored in the MDB database as a function of UNIX Epoch time. This is a representation of time expressed by the number of seconds that have lapsed since January 1, 1970 UTC.
Example: A value of 1529048800 on the last_mod_dt field of a request ticket indicates the request was last modified on Friday, June 15, 2018 7:46:40 AM GMT, or Friday, June 15, 2018 3:46:40 AM EST.
Such functionality allows most content to be stored in such a way to quickly facilitate time calculations, such as the Time Span defintions in Service Desk or for reporting purposes. However, this does prevent date content that preceded the above date of January 1, 1970 UTC from being stored in the database.
One can leverage a variety of online tools to convert a UNIX timestamp to a human readable equivalent. For example https://www.epochconverter.com/