Block insertions on a mysql table with specific value
The most powerful approach is to wrap all the basic operations like INSERT, DELETE, UPDATE and SELECT into the set of the stored routines. That acts like an API to the database and can be extended by any desired checkouts/conversions/calculations you ever want. If parameters passed to the stored routine meet some conditions you can INSERT them. Otherwise you reject those data without inserting. 

Same effect can be achieved by trigger BEFORE INSERT that look like this:

BEGIN
  IF NEW.id IN (100, 200, 300, 456)
    THEN SET NEW.id = 1;
  END IF;
END


where id=1 is already existent record and id column have UNIQUE constraint. But triggers in general are unclear and non-transparent tool that can be very difficult to debug. Also autoincrements and triggers can interfere with unforeseen consequencies so it's better to avoid triggers as possible.