SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fae136afdcc6ebd9455f578977894bbedb25d9a022fe9e63f1c250dd909f040' 
  AND token = '/0s7+iXzZtvpC+DVWpxUr9qh8fbBgXeZUvbzHO7RMIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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