SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35240311cb35313190a9579a6f857b037948c71abad57e015ddacaf8c8928361' 
  AND token = 'Lo1wUuAFGUuVc45GlPJ4niZ/ylKCX589OZTXrycfdgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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