SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a113d61b78cc743922fbb0805bb085b6394e17bff2e79b7be8e69552011e3818' 
  AND token = 'nTNrLcd/ybQ1KqKSQO30JHOZBGkMel//z/8XQYbVfT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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