SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '62a3fd2f051f8472fcd100dc56d58790ac671d253af1b5541381235e5c5c3a95' 
  AND token = 'qUTZsbLS+XLyojib0gKx8shlZnfBnvOOt24ztDsP5CI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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