SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e7dcb01db062585b7f3e9e5bfe0ea1743ce8c67fbb3071516c75615b5538874' 
  AND token = '9NBLuXqcxfAu88MmlkA3UhaejSSrXIoRCOZBrcYSnck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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