SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dc5d7b79711ed96f63a8634c4bd60eb0dc41420b5237166a3b866587d8b2a77' 
  AND token = 'D6k/wTkDIIjkHjTWIHttZo7YWWvY0NpKzjMWWawFXwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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