Modify A Field Using Pure Sql

I have a program that will need to update a certain table entry repeatedly - so I want the transaction to take place without using up too much time or system resources. I basically want to update the field with the current time i.e. Now(). Let’s assume:
The table is called tblExample. The field is called LastTime.

I could do this very easily using record sets, but I understand that using pure SQL is much faster than using record sets. So, how would I update the field using only SQL?