SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83fe9b83c912e88a6873cc5d9dff207c32a70c7620fa58104370ccb6f1d0547d' 
  AND token = 'njAO1iVXhSSmgSLLaXVrP1QEaYuZ6cYN/qYNQVLD+Xg=' 
  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"
    }
  }
}