SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd71c3f6fa0990b5a9956374c2fc796def501257741269641da9c3b6f536d4a21' 
  AND token = 'AsCyUpKXZEDs9QQTwli8+JfwB8U5IV2kSXZhz6FtPt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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