SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd12b96eeb7c8c29dc8b6603493dcfc7e520924f0018020a4e0f528074d9e1aa3' 
  AND token = 'uaCowixwX74UERlTToou936sWpnljpODgvIKz098B9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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