SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd736864e58ec67b048718c89183b0ad0fe70d0ac54925ec9f073040ebdf21650' 
  AND token = '4USFK4UiZVmRflkHrPOJfl1ESGmb0fLNKGjD5L8Zebs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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