SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e6fc0ab3b3277b455b38a79dc32eddd3996b38013146a4c8e1701bd866dafb7' 
  AND token = '5wGzE4KleT9mazZLPxylbskkEWpcLrtZx4fTYYQ8VsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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