SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '826d9f5f77f38c797319175083b1b5c08e6f95af9ecd812692f747dcb12ad6d6' 
  AND token = 'ak59DtnJxPjhrzi4KX8xesSLnvlyUYD7JsHKoIV5uLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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