How much slower will the fetch be?

Question

MySQL

Good evening.
I ask for your help. How much slower will information be selected from the MySQL database if two fields of the INT type (WHERE A=23 AND B=13) participate in the selection, compared to a single field selection (WHERE ID=126).
The table from which this data will be selected contains one and a half billion rows. InnoDB.
PS is there a difference in the order of the query arguments ( WHERE A=23 AND B=13 or WHERE B=13 AND A=23) if there are much fewer records with B=13 than A=23?

Answer 1

Depends on which indexes are built for the table. It does not depend on the order, the server optimizes the execution of requests.

Answer 2

What is the question, take and make a request descriptor, and you will find out
AND more profiling