SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ff93a6ec6f4f77b275d96ac1130b28d5dff15368d7feb30a6a18dc131b4e6a' 
  AND token = 'WLz/MBg9n0GKHE3I9wUxI2WiKxkDAjd1LOF2dzvKSYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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