SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '395b9370f44f236944820f252e693dc4af5325c8e68c2819f6df296bc7f736c9' 
  AND token = 'SeHlY79rZDBPWi5zV19gu69HHecKizZGvsJfk7voJos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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