To enable time selection within date range filters choose the below option from the configuration settings. You may also want to increase the width of the filter widget so you see the full time.
Now your date range picker will show time. One approach to setting custom range relative to today, is the “Relative Dates” option:
This allows you to pre-load a dashboard anchored to specific time - for example today’s date and then choose how many days/months/quarters/… relative to that anchor you want to show.
For example to show the last day (24hours) you can do the following: