SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf98145f6720f9897903115b842ebf835eefcfb989a4672014008cd812aae2bc' 
  AND token = 'RkfPuqyqLXehzynVfUoEa3c+UkG9gYxG++DHWYtjbMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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