SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4b3c97b5f0f8df1653422640604b50eceffab003e51f8c79e3da517668e0bc4' 
  AND token = 'yXCMePXZ8RYBu9K2zCzlczR9gp8WXW5yWX7AT0GTo7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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