SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42f13d5c2025846f466b9b8ca4ebb7dfd3a81ef7044b5cd9f0b1b2b492f7ac32' 
  AND token = 'Cu/B+x4JP7kKZ9mYlGmdsyU0PPspmgA3wMtF9gK8HWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}