SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd2cfca649c75ae09c3b5f496804aa3d7cab97a18f4860bcbf38fb292976e69f3' 
  AND token = 'rMj/a+Ng88wQ9puSp4Qi7tQq+SThW4OXVg/onxTA1ZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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