SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0d8874475f05b6c740b77316965c2390ebfbe18976b06fc4ae390712960f538' 
  AND token = 'S5M8F3MvE57LzRiZnsRVhVgVwWQkD+l6ggBA6WV4/3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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