SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '08e0447360b0fb2a621c5f1cd8499da78270208833b5f342236b02b7198a0b85' 
  AND token = '7DDcYApboBYx4rIJBnexnagimhDMHn09TEvPYLfpKV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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