SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e44824e8351a76a89523cbec0f64be70fda3de4994d88f59749e02d9ab6cab37' 
  AND token = '+jbXCpehf99wAmE13+tbugGifovDw1GCCIrMK+MsJBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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