SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '61349b55c22631a43615204506cab708c23d9c2bc94afe51f29f5516a6bc275e' 
  AND token = 'LRnaXxGebLB8w+4gmcwKx/mCjnbpohmjftI9Ry/LQf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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