SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b35149c30835330a67bd5f888aef5ac7858bc0fe9eda065daa90b82200ec3f7' 
  AND token = '8TfYmQJfXRitAhFDBCbHW3wzawd6K4irqIfxO8SXLiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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