SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '473423b6b36a1ed42d911214e58bb3baa926f1d5a8c05de27b9746d8629dd957' 
  AND token = 'jD6DvvIpO7k4LQBhSgum+3ZLY80mi32CZQBKAEUmSto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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