SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e0df000294b010bc1152c510622f55af7b324a26b31df31f89268892f4abe433' 
  AND token = 'rqt4l6CMEJhWqLxYX8pxbw+9HKxDRx0W3iu6qL5GL6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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