SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f65324086d7219fe20cbed70657a9963c2cb04c418b962637ca03ef0f1b5a04' 
  AND token = 'zsxnif+149gixOLlVldlRkZFOJIBgURHKkrGcn0G7Bw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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