SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c1fcd1d2761c1dfccca70354f03cab252df4b27acfea9c57a7721b780fa2f060' 
  AND token = 'fwyTsCL6QCd0diAFxHqqI3Jluhi/Hb03RKCEkjOSYZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}