SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3068847cdfeb4709be209d5cb202232a41bb9a196e3f935e86875edcf142b0ab' 
  AND token = 'rt5qtIbe79jOnvgxkiTjkMuFqJj/RtJ1kg50AMaxUMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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