SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a546beda4d5c9716876097abf3a7be3e8d099bdf8b8fdf6e3d254826aaa196b' 
  AND token = '3171HmdjcF80+BNzs78zdc6hqP8PnfTVCTUyBbUmG9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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