SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51132fd535773006e7fae9e8023934a179a678f463a6aa611c2297047eecb60a' 
  AND token = 'iHkrFSTWt8VkNFKO04SroN9HEDgTtiWuOueww1b0k9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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