SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '976f73142a2ed1ac9228f5b82f4838d67ca16b5ffa6aa16996750fdbc98857cd' 
  AND token = 'TRk83AHnS7RqoyEo3YXgI65MxTWcWAjQ0GdlcwuKkbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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