SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '321d8c45f55aaaf5c925b8a7974b079aa301466a178174f155852b061c475cb1' 
  AND token = 'hfdFvRzaRm8FMKxtmMnwCCy/Gk7CzGH1NdZEAaVOxb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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