SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fc35382cf34afac73279df5771d66511a5e4f05b9526630c85c28a309866858' 
  AND token = 'rvoIBcDMgfUPLZg6HPjyNXJvxzjcly7LfusMeM1Znpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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