SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a35d259942a9bc267489313d0580790edafd55487a035e068a885a5a170d6377' 
  AND token = 'LVhT6rZLmAt71V8EZW4VVvzgXwIBoXfRxNC/Eq8+eGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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