SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b59e80bf59809b8b1fd0527ba4849f304be1eab7802976f649b2d92d9f43d818' 
  AND token = '1TEn/1ZiU3v3MYOBObkpZcn7yINLwhgV2jRN5p+lo1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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