SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '87f3a0b758e9fbf3741826eb7a037d22b94cb31724087e1c0395d8aac1db7971' 
  AND token = 'jzjocB5/LakFeUMK8UiH2VWjwqJ5vZHY2ryA8UC6M3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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