SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c478ddf9eb6aaaf819221313cb73e102fc314dcb855475fa6def9c2b2a86802a' 
  AND token = 'xH4MSRDNvjeWe5Wg4VGXAkUIGO06To3AkUUj4BkUvgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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