SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dde6cedef060569bc566876e7502696ed4e0fc48aa633be72ee05438f1f31b81' 
  AND token = 'moedAmfWEvWorAFlPtbQzydOdljnvev4j6jGeiKh5w8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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