SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '727dbc29ee6147225cb911345106c458de302f98c7ddd561a077a46f5a3c0409' 
  AND token = 'nBWwNAUPuRFkP5bDeF6h6WqO23yNC5KKFT57p1C1xEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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