SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '935cbcd7412a68c113cc1085f05febe8f9e75ea33bfb3002d022c09b4214d9d6' 
  AND token = 'u+E9zPph8U/QGCBJOvt/wXTgVNKdJ8i6V9fICbhPFrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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