+ AA6YQ comments below
eQSL and LotW both accept time mismatches of several minutes; a few seconds is immaterial.
In your first message you quoted a message saying "no QSO matching callsign, band and mode" - if that is an exact quote, then you should be looking at callsign, band and mode. Of these, perhaps the most likely is the mode, especially for digital modes. Note that the ADIF standard for recording digital modes is not always what you might expect (e.g. FT8 is a full mode, whereas FT4 is mode MFSK, submode FT4). Some logging programs don't follow the ADIF standard exactly, adding to the confusion.
+ Rich VE3KI is correct. If an incoming eQSL confirmation matches the callsign, band, and mode of a QSO in your log, but does not match the start time within the range you've specified, an error message like this is displayed:
no matching QSO within 60 minute time window; closest match: 2003-07-08 20:09:40
+ I have the "Maximum time difference..." set to 60 minutes.
+ If the error message "no QSO matching callsign, band, and mode" is displayed, the problem is not in the QSO start times.
+ The error message displays the callsign, band, and mode reported by eQSL; filter your Log Page Display to show all QSOs with the reported callsign.