SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6f3a134737e8acb5e196ac18b652c0e133d354e85b9b8a9869287f0ba948d9ba' 
  AND token = 'Qd1GIUJbVAxhq9UyMJKRJZ9Oi9rpI2ZgZiyzRUmQzTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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