## Bug description

personal_api_key.last_updated_at is updated every request with API keys.

This is one of the most time-consuming queries we do against postgres: https://metabase.posthog.net/question/344-most-time-consuming-postgres-queries


## Environment

- [x] PostHog Cloud
- [ ] self-hosted PostHog (ClickHouse-based), version/commit: _please provide_
- [ ] self-hosted PostHog (Postgres-based, legacy), version/commit: _please provide_

## Additional context

There's a half-hearted attempt at fixing this over at https://github.com/PostHog/posthog/pull/10383, but this was shot down due to UX concerns.

#### *Thank you* for your bug report – we love squashing them!

posthog/auth.py
import functools
import re
from typing import Any, Dict, Optional, Tuple, Union
from urllib.parse import urlsplit
from django.apps import apps
from django.http import HttpRequest, JsonResponse
from django.utils import timezone
from rest_framework import authentication
from rest_framework.exceptions import AuthenticationFailed
from rest_framework.request import Request
class PersonalAPIKeyAuthentication(authentication.BaseAuthentication):