SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f2b8841fb48b6b76ea1bf5c886a7b8782b6be3e9a961aecdc403e0b86b64a71' 
  AND token = 'zm7rxSfj+AagESeIRdHV4jHawSDTuNpvrisAAxkJFZU=' 
  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"
    }
  }
}