SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16c0e3e020619090c27145fed5f9fd9964cf23c9ebf5c15f813db5dec73a3dc4' 
  AND token = 'cqCFbdrwQVFn3Fd1qPcxxJQzWBzSAEDZZ32ahRvRQP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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