SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6f1dca7177e94ddada501f94769f838c9ed24b311c61f8297d8c275b001e250' 
  AND token = 'Cjs29L9Xwjf2OjdS1cYB31FfkE21NjeiCOI7u+IQ6n4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}