SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '303e96380f6e5d93fe1bbcf924a70114a0ac25a36489eea6bd02a70db5a8009c' 
  AND token = '/xLtfM9oJYCDdXzlXQlyiPhvMDrXCIZ666sVEzQgk/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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