SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67c49017046937bb0f10843641c0eca41bee35411eda72f48710c9967bba57af' 
  AND token = 'KFiAn5vXkSoC9DatOzf1W1QcIbeYuRmRUV0meaQlPC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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