SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '40d68ec6893ef38cb763c08a83e8050496e4a7b09a632362d86242a7cc4d9721' 
  AND token = 'kv5HWzI7T/2mKvqD0TlMGYklJFKB+EZlO5csakwJfQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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