SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '352a6a277921372aafa23166260be8fe037aa395aca67140a1063f8cd366df6d' 
  AND token = 'D/Fuke2ZVAEiLMkGBZK8QipRuRdbEVvC4MQgipIQUjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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