SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81e057578c1582421996c5401e99dc876e549e70f4ef50de41ea4b53309f0a29' 
  AND token = 'V2VsCgDbQwpopuIYZRjejLoFsuQ0TQctUU/QSpatQMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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