SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb03519cdf91f89b533274d24b0c930183f6c85ba27be9aba3d459a9dd8acb97' 
  AND token = 'o8NN/zVwzaBmaQlVG7CnRvtuQ2YFY2eJiKk2zo3Z4Kg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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