SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b5c139bd8eabf793e1ba06c9cd0d57cc10f63d74ab40efdf84a72ab24a8b9e8' 
  AND token = '5i+FRcgx9o1DMMPgHqXlIry91s44Z23hSBKdJ5O4Py4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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