SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35ed049231cb639444eb7e935c9755c1415eea94449273aaa878ddefc4451840' 
  AND token = 'vIlhcht2pqqHgwT2SerFnf+WmMZx6LxOA2SJkDTUOCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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