SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b5b59b23ebe09a6677875019df5f523a58eb8c53cd6f2ce3964d72980df8fc' 
  AND token = 'WTzNnmNWOsSgTeW0l6C2+2AWaLkfvKAKi9Tt3WNYias=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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