SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a49e7b65fad013d8116ba345b2dc6b89c43a44d437c09609708ea9cccf3d1f0c' 
  AND token = '386tbVe5SaQBpGjfGhdCd9iphO9FF7UfxrFRyjzsROg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}