SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '485db28ac9ade87ae4026bae2cc5d753cc633a134093bff8d732caa8cbdacd0b' 
  AND token = '1iClexqeMoLUgQb/qs0GCoyEUXFkIoaLcDCajt9hBAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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