How to add a condition on a value from a select?

Question

MySQL

There is a conditional selection:
select field1, field2, "prod" as env from table

We need to add a condition on the "env " column:
select field1, field2, "prod" as env from table where env = "prod"

Tell me how to implement this correctly?

Answer 1

Um..
select field1, field2, env from table where env = "prod"

Answer 2

And what for to filter through where if in a column "env" all values ​​are equal "prod"?
Maybe so ?

select t.* from (select field1, field2, "prod" as env from table) as t where t.env = "prod"