SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce9c8ebb0f14c7c981d178c5baa5221d9a157b5a6823c239bc472bacc57d561c' 
  AND token = '5b96K/i/MrLbmNf7HZkaVREdAdOirXF4oeOevU4H9K8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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