SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd212c252c6cae8d0a23528aec257e5ef21510f843b56f74a50b67275033c945' 
  AND token = 'aMft5+aJ9UpPferYS6TbzIFSBfMh4oZHK8IsOZIIyG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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