SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d5bb688074faca36d66cb036081d7fd408641e15a29b2a7a110b3cc22246378' 
  AND token = 'n6mLMlLGKllqzMxJDfFlXXqFudhKkDBdd3nLv3zxEf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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