SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0e42f7c8b49ada20206b344447c54621df2ab282e074e2f40534276dd9bc510' 
  AND token = 'i4TaE/5+rE9LTDGs8iHu2Hp14nYRPvJKsxKNWEOGqU0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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