SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9dfd5c20636ad067de12f447648471d27659c654782b1e5a376c2b6b6e8d409f' 
  AND token = 'hY+jEULsHSDF4wFRyryNjKXMLAorduWlMW7DPwGqnwk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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