SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '39b8cdde1122a00ae264f13a326889e15e105ccb6c6dca03a94e8895c079d73e' 
  AND token = '5Ay80/YhsLSuIWszjPuGD6vSQBlULnDj+n/Cq2+ag9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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