SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b2c872e71e551f9699212d885f84f381497f1fc6ec79aba99b73f594182370ce' 
  AND token = 'tQqiNtakII3ve0vjpzPU/iUpNLLwfbNxHzrjMrtBgIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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