SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '839f8b4e048de77db34b3d5658da7a9fe39cd01675cf4b4b587d42bc1c8f9ba2' 
  AND token = '7RZH9KdkU0hKsJQA16pUWZgWY9v0GVh45sRn6oDTmrs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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