SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '604f07114b9b0a390a0937fc685821227631833d25d4312868d75488019e5f2d' 
  AND token = 'K84NVc5U2BKHF6Vqqnzw4hTwHCrs5apV/2uuS3oGwJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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