SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21842d0a259621cff688ac668a54c630bcd6d43d42ab9fa4dc8ec5c43a8ad7b5' 
  AND token = '5HzIhp/K14uYa4FfIjmoslFqErBI3rJtu9qWQw+YuDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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