var timestamp = DateTime.Now.ToFileTime();
//output: 132260149842749745
This is an alternative way to individuate distinct transactions. It's not unix time, but windows filetime.
From the docs:
A Windows file time is a 64-bit value that represents the number of 100-
nanosecond intervals that have elapsed since 12:00 midnight, January 1, 1601
A.D. (C.E.) Coordinated Universal Time (UTC).