SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2b23684bad7c1ce86aac46898be651fa7ff8ba724b10648103fd60c268b0a3d' 
  AND token = 'fnjZp4ROkp53WWyrca1n6wEY3CLSuOqIzlRdxTFxWCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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