SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d96e15bd803138123ceac98cb59b88ccbc15a40eb9639d42e151fee5bf36583' 
  AND token = 'qUvlu1vd4xzPrMdwP5+qYaiW+5+2ZAWAm9AuxgApBTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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