SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a23e950639462042b834bf9a524d8fdb8504d704b35481d39080399656391a5f' 
  AND token = 'ZG1vFzW9YK2TtiXAbVJ/rFbkVxNkeJ8n2Ayau/IvxCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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