SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '9b6fdfc400fca1647c389ff9a743a9e279fde32fb908fd9fd7cdb863b5a47e6a' 
  AND token = 'Aq3Mg0gC4Z4y9XmJXUWC8jN/bDkON6JWhMVGk2JDj1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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