Get date and time information from timestamp array of logs

I’m trying to use the time array using the logs generated by PIX Hawk 4.3.3 (converted to .mat format) to compare with an external information. I import the log files with the Scipy library in Python, the data contained in the file is imported as a dictionary variable, so that I can access the information contained in this dictionary. I need to compare the information contained in the log with another log that is referenced by time (YYYY-MM-DD HH:MM:SS format), so I need to synchronize the information of both logs using time. However, the time information contained in the log generated by PIX Hawk is based on a timestamp relayed to something datetime, so I need to convert that timestamp information to YYYY-MM-DD HH:MM:SS format, the problem I I don’t know where what is the time that is used as a reference to generate the timestamp or where I can find more data that helps to do this conversion.