SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56f7f3c23be3ab257a228141b40103e524d4ed2d2d0659a4e8adfd3ecf09ab9f' 
  AND token = 'XlL+n9PAXZUlWzN6yRyA+HKnTYfH+VzZrjmXTdFJTFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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