SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c5a45383729685e38f0f67ab0e67945ba352dd3345153c0c0af9486c6db578' 
  AND token = 'KE9/YQsIJdLnTBmE/miuwB3wD2wMTPQQh+/6VdrU720=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}