SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21e8f9b13dae705569eaa542550a425851afc424d609cb47dbf7df057e343795' 
  AND token = 'y4xLiwEaKeXqctMu6Wgma2ZLiRsQTFOiRipVgY6bXZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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