Move from SETEX to SET EX

[solracsf]

Summary

SETEX is depreacted and may be removed: https://redis.io/commands/setex/
PHPredis handles the redirection if needed: https://github.com/phpredis/phpredis#set

(+) small code optimizations

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[come-nc]

Please avoid mixing changes and refactoring in a single commit like this, it took me a long time to spot the actual change.
Mixing them in a same PR is fine but at least split the commits.

[solracsf]

Please avoid mixing changes and refactoring in a single commit like this, it took me a long time to spot the actual change. Mixing them in a same PR is fine but at least split the commits.

Noted.