SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0254cf12dcf7f4d59e931e941ee996d4a2dc45dc9344f7715ab1f350b2d26d18' 
  AND token = 'UVJTulv8xJLsx+wEEBHIwiL36tVZRHb+kZnpX/VF44Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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