SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '909ee158bd089733d9e9a603c79a962364721a521839002b978f156dd67379bb' 
  AND token = '6OF1VQyxTssgPZCwPl1zH+MMFzW4RvgDSUTvYqKXgXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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