SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '631d51b6dda14a42ce925a7880d33a6879d125823a0e7b6efa3ace8475bdc3c2' 
  AND token = 'qWMk5thZoqOfDIULcmMaEh/ci7WdwNESjik6jKtMf90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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