SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d27f39bc7dd843b23ce27b7d8502a4a1120253a4bf316ec18183ce87d36d23' 
  AND token = 'gKlspWq2DOCLvnsxL/haiw8PNig7yDrkPmbaSDpcA94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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