SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c621f9f9747af85c9a7f27e99ba7533ba348a0eb4a381b372cb170bcbb02d6c' 
  AND token = '/3Hq4QgjRzsx4weWszYg+yQAdyF/vr9Pzk3zqJXyY4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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