let me second Jagan's suggestion to calculate the desired logic in the script. I'd probably add two Date fields and store the Date representations of the two dates there.
However, to answer your original question "what is the correct Set Analysis syntax for this condition", - the accurate syntax is as follows. You should formulate an Advanced Search condition based on the field that you'd like to apply this selection to. It sounds like the Row field might be the best in your case.
Judging by the look for your timestamps, they are probably strings (again, it would be better if you converted them to proper timestamp fields in the script). For strings, the Set Analysis condition would look like this: