SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8294ce6bd6cd837ed73232f416bf13de0865e770352cdd8ad002956329f1334' 
  AND token = '9wcueEX/B0p6tXiKqPYWTVrTr1YWuHhUj/GS+1t3rL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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