SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd35965b9884796c30903ae01fcb103d979e7db7aa89a356a3af95b24bf20a4d3' 
  AND token = 'isT+IQoeBvMyUMT2F57xWbv//cq8hchXmTVF79wC7V0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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