SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f010811bca983a3feff5e23614f726a7706c48291e875ffff8b904f17a74a5d3' 
  AND token = 'kj5Yy1lZMPDpLnZIyZGTXSI6biwgZKD1NsYjOyQNTW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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