SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bfae284d159812280baf295c6533eea2c5df5de5639645d3746b08e14edeb6d' 
  AND token = 'ewh3N8vgzrNnbNpMzbDC4zs4VNDmAr6sUjFk4AiDOeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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