SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6485f3fed2bd102dbe905a2bc721ebac9ec933c7041ea1255be218ac640f6a' 
  AND token = 'pbwrRoYJBVy0JQHv7ZMzXFxfhxgorjMvoyqkLbSZ7cY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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