SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa18a75614251f4e74c6fd9183a1329a84d7b8f378a672e69a1d58fdbb4a990b' 
  AND token = 'yLBFG0ZZgZBvwoDEpZ+hVQvF4A21/zg/vvozThZXL9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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