SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c8ef2b8a722a48f2ce18c0812699f28407bb3744f3b23eeeb599de0193047c43' 
  AND token = 'JCZr2HWMd0Ifo282LQu+ahD8tD+0RW8ATKFQ6WrS3i4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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