SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3446d3b7baf18bff8b40ca1d1621d6009582382d9fbdaebb8c2a538ede2efa1d' 
  AND token = 'u8qLMvizzknlhqq/chq3tJvYXztXmffyh+JkZJOhsRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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