SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6e3018e17224ab08a1e7ed6060975060d771c1adfaa2553dc0b5fbeaa5f02ff' 
  AND token = 'tFRODBZiaoAQlJpt9sr1RIvLQtFsAQS/Aq0C1ByZK/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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