SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cac55426a9ea53274a86d047ab5a7903f1f6038b1b68ce3505f97f1e578ac4d' 
  AND token = 'WikW/CAMGwYBw1OLdfxwZ1KpJVRuAfwU1BsIQ+7HQYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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