SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3f0b5c1a7d7cb1425492995d5ceb9b4f4a6ccada58f77381e82a406c249d9e5' 
  AND token = 'vwnXFlSD0w1dGsrUJ5JNYXhNpxrxtvJKSr0DDdgP8MY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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