SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '596859fd66fea04740b3e5fbd1ed9c14c3e6a9a96f63af9dfbd699f5c8ab346f' 
  AND token = 'qlcjZlPhheUScasam346dIqmgxnF7KaiU6cTdUZygeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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