If you need a quick check to see if a slot is bookable then the bookablity check is perfect for this as it returns a quick yes or no response.

Using it's LetsBookFor Slug, check if a slot can be booked

Check Bookablity For a Venue

The venue slug as provided in the letsbookfor URL

Venue Slug

The date for the booking check, provided in dd-mm-yyyy format

When should the booking slot be for. This doesn't have to be a display slot. Provided in HH:MM format

How many guests are trying to book. Required for yield management check