SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '843d1f4cf5c28b8ad580a88a42df2299ae830a2de8b109db3f108f29a4450561' 
  AND token = 'b8UeybyQbamXUVri/rBWsCqyAXx5lIMm7gFumwunmSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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