SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd557b96b650e9b57886601eca546d3a57f733a8eaf8539e67292d18fe892854c' 
  AND token = 'UYOCC9HQJfCUgOfXmi2WqxD3LrxJviBUI5HNHSLoHu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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