SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b652f82ac8a1209d81e3b96df545edc5647c93a4dae9d12416cc8ba780cb2cd0' 
  AND token = 'y8/LoJHGuo6fEyWDpCl7gwjiLGn5vJXyfISs3ynqs5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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