SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0cf2711f7deedca2494c74ed6c0cde1a1849472983ef654f7d0d2a03965a4858' 
  AND token = 'ZkLOxLGgtF+qwrhJHOZLgk3cuyE9wSospSheJvkC04Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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