Excel export provides an option that reduces export time by changing the format of absolute time. Usually the absolute time exports in the date, hours, minutes, seconds form.  Such as the "30. October 2021 09:30:51" for example. If you toggle the "Write absolute time as double (faster export)" option the exported time gets structure as a double value which is "44482,4084457153" for the example described above. The value represents the number of days that have passed since December 30, 1899. By default, this checkbox is not selected. 

Find more details in the online manual for Exporting data.

You will save time for exporting large data with this option enabled. However, you can display the double value as the string within Excel. You can do this under the Number format tab by choosing the time column and clicking the "More Number Formats..." option. 

Under the Custom category enter the display Type, for example: mm/dd/yyyy hh:mm:ss.000

In the sheet, the time format column should change according to the entered type format. 

Note: Custom formatting values from double only allows milliseconds. If you want microseconds, you need to export without enabling "Write absolute time as double (faster export)".