SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c1ea4f99ff391f45928c23295e509bb2bee43a2232a00b5b97434ac47fd73b4' 
  AND token = 'tEEE4QSrNzJ6KNi5tOmNJoYIctruf1kQnF0YALT1moI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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