Create a query using an enum
There is no way to do what you want. ENUMs are inherently a unique textual representation, stored in a special way. You can't add a dynamic to them that makes them useful in any sense to an INTERVAL. 


MySQL doesn't really have ENUM types, it has more of a macro over intergers (a hack). MDEV-4912, MDEV-4913
MySQL also lacks an interval type


For these reasons, the best you can do is probably a lookup table.

See also,


https://dba.stackexchange.com/a/177075/2639