SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71ffc649bf6b8afb1df09ba6cb8cd30602b0f07776c28a225b855c7dccdb62ca' 
  AND token = 'xucSOztX4TXpdY8rROvSIVh+62UpRV2Lc8vYH25CBnU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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