Explain how you would optimize an existing database query that is experiencing latency issues under heavy multi-tenant load.
Assume the query must continue returning the same business result, but it is slow at peak traffic. Describe the changes you would make to the SQL and supporting schema or indexing strategy, and how you would verify the improvement.
| Column | Type | Description |
|---|---|---|
| case_idPK | BIGINT | Unique case identifier |
| tenant_id | INT | Tenant that owns the case |
| status | VARCHAR(20) | Current case status |
| updated_at | TIMESTAMP | Timestamp of the last case update |
| priority | VARCHAR(20) | Optional case priority |