SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd726505055b6dfa1d8ab45df7f3c840412969aa6867e1b79b5cf90840aa5e557' 
  AND token = 'ZA9zDSHYZwQIBBwfJM1fxgBY/xoewxPYvBsurfgmoOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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