SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f92347fb6b3c5371e0a38b345695a9b445cecce976795549eda3c97b755de998' 
  AND token = 'sOSatbesxTibrpi7agvd9VxGRnUpflEYtg7qlN4UWhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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