SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '921310a1e24bee4f506a690f37c71724ad9a9630cc1b7950a6cc15b9222ff183' 
  AND token = 'ELRI0jP3hTPdmCmC5VqqLCREZAgZXVRSXnW9H42JRaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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