SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '668b398eb486072fd77df081e0e7dc430ba5df39669ef97512c2364b30b718c0' 
  AND token = 'APQGapqsBYYKAZh2S6WObX2pTeX1KbfgIdoKVLwXkhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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