SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '683a478a4af53cffffb028f9d92ddaf7f4fb03a5065e90d5be44bb6e0c42c93b' 
  AND token = 'nYS94ZitNf3QMYNHsYiV68b1pqduoimIO3S6ghdMMNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}