SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b9f411ddc3eb059188272135837ee984b24d8688cbf51a29ce43075c3c28c8d' 
  AND token = '4mhxPZgdEYGR0SdIr+oj47nz4A6wjKflXtIrR09YD5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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