SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '426874dadf17138748bac6bb52254db1e1986985175744649c3d83aac8302e45' 
  AND token = 'Jq/kOkA1mGnSBEDu3RUkf83m4xmbxtH8R/LEjMy0frc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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