SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31767e6bdb347a839c25766dd112bec378f6f97458546ab9836e517b76e2848a' 
  AND token = '2ByluN4djMGAygHVwDOpwCm4LmSK+ihjVdvu4JLqg/Y=' 
  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"
    }
  }
}