SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '558e8b4df439671e8d3c0d16d67cb63a0b47573871d62eb41d5cd2f8eae7d3cf' 
  AND token = 'YuQtELgbqppV3cIBSb9hQ0PkwOU1rirmxhtMYXmjyKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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