SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6ecba38b3dcdc2228d52c425510fc2575353abc0d6ea6085b3f4c764672c407e' 
  AND token = '8OAITS8+NfuF37K25VnKgMfuE7HJq0xkMw6ArmwnB+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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