SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52aa9c700f4b0306d6d8b658b934bf149af6cc3a84fc094205b80fc88e55019c' 
  AND token = '/PJZ98pWf1K4i/zIZVEZJhAj5Fypm7gLk0Mk/I5zGjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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