SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4b799010dbede2321db05b9315fccc53efbff36de9628261896d74b6c20ee2ed' 
  AND token = 'd1HOdIMBRK9hbRGlvRi82dXvhNFuPyrI1ZrwJdIHigg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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