SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52a6327581d98bc57f7dfbd9b9bd7602c648eb5ef74e455e1403a6643561045d' 
  AND token = 'ewG3SXnN1sMquSqVwJCBd5EZ0qwLQVlJtvBMowfRSmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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