SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3877167e161b20cee52ac62d38da60d2289f780f48d50abc8c5c79a95aba9d93' 
  AND token = 'Sipx93RAoXbttLwAfasucvNyHGI5kSxznfOImZM3UMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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