SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c47d648681d642a8f15239f5fa70ea893f6f368fc590e5a48025dfbdb2f9b1e' 
  AND token = 'jrkCfYvr0rwgEXQcl+5GhOt+6dBAzcv9/BJ39TtWSy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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