SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fa2898a6fc129da4b78dbfd7711cba568267db8bf04da23d2795d76b663fc3a' 
  AND token = 'ahZxzV2U9FWQ5AH7HGAY8kg1FYdikvZB1MjEbPGecpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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