SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73958d8dd6bd1d1ab3bd3866c6c1b8ab054368497b76c7b07666db32df016426' 
  AND token = 'WHe+ZgiSkqgxh5T23xiKgIVpvOw8oDaBDil0GCBhKvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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