SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '647fc4108f1914dcc3917608d78a426720a20eb634e1e1409ba444a325341580' 
  AND token = 'ETLKHFbWWS5nhyHoLmp7H25CzeEK79goiHaiVXaDW9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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