SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5286ae70b7daf1b1696f3454d747fa0b6fd1436ed05740eac79a33b0cf791b50' 
  AND token = 'K7h4/JmrhGWnA7JsOdZ1bxwL8CC0Hc3JiWpNr0TLJOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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