SQL timestamp to specific hour
You can use current_date (without a time) and then add the 7 hours:

WHERE created_at BETWEEN (current_date - 1) + time '07:00:00' 
                     AND current_date + time '07:00:00' 


(current_date - 1) is "yesterday" 

Alternatively you could use an interval: 

WHERE created_at BETWEEN (current_date - 1) + interval '7' hour
                     AND current_date + interval '7' hour


I prefer adding a "time" as that is easier to write if you also want to include minutes, e.g. current_date + time '07:30:00'