SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7396f887c245a8424d0cdfc84220a4969775ada86e03240c703ec7ee0d6e9553' 
  AND token = '0VKZYTMMQ4eHNQhGn6P79QQQsIrBAJFHnzWv8hOHf98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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