SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59738ecf24e30e9faa73032b5c493f7f68c34ec9c17d23f4b36670b0dccec998' 
  AND token = 'wEeh2E6O+1EMV0GFDjVtdKvBqswKcVxyBQYydZt5II8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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