Start and end of the day - WF Backend Call

I want to query my database from the begin till the end of the day. What hours should I select to ensure I have full day covered.

It’s a backend call parameter - so need the backend call syntax.
Now it looks like this: (and I assume I am loosing some of the elements due to hour problems).

From=2024-04-15&To=2024-04-21

This PM, AM and day not starting at 00:00 is very confusing to me as a Middle European (we use most of the times 24 hour clock).