SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '43b5350f42e6bb2e0586e74b81f440f4728dcf1f6992260f1424f4b83df1cd74' 
  AND token = '3aXfrC2+IV+lhQ84FUFJhV0JsVYQHqQSWQO8G6FfyL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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