SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4703efe779565eb25e054f43b0264c88c9615aaa71515a33b458e30289a56ff4' 
  AND token = 'V+Rpwha5WMng6sBseCeXlvOzHJ2K37pofzjRFR0GE0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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