SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c69321e1b172376bd142db1bc4057c67b628ea311e385cbcb49a903afd698ade' 
  AND token = 'qWRSD7Gu8rL73qjWrTDBdqAoxJInwnwXJf9qLg+KN/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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