SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f77b546d8b45b4c4484386498235c0769b21c9334f07c3ec502565ac3f2c269' 
  AND token = '+0QGf3seX70GBDoZx5zKpjJNYxOUmlaYkhdyyh8QkLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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