SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eecf28d232be5389478215037b5152212d840a2efeb83b631654bee328e16f8' 
  AND token = 't4HmppWsPRNxrOaYxCUJqdJi/7i1Fb6Eq7Pur3nkaZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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