SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efc2f79056949d34b128229ec117150c43857797c3d5c157d9ff362ac1650406' 
  AND token = 'BfSDuLMgF4gVukvVG3khQBdo99JsrBOtnePz8GZgHu8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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