SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ab51c2c6394624a8f2d7dddbc5972e064fe4a2dac8da56947a10c8af23d770f' 
  AND token = '1qstUAxH6FMuC36MAr9vrIp0lGWuFegWKrWEluKf10A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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