SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ca28895cc33fa775f9cfe916f762b89a042dbf676da1de92271cd188282bd56' 
  AND token = '3zNgVkAd1rV/x7+SCNhIJVYH4s7CdSXURE2djiy76aM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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