SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '65694e2f51867fb71bda65198183393e676a5ca5291944d33149bb4f017fba0b' 
  AND token = '7KqDWvdQYE5agImwv+wj8jfUFP40FaacTnBikiAwOX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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