SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45850a45d7447f394db7335d130357f63a93fbaa7bf0c21fa9938b191ea21a09' 
  AND token = 'sddAosGafkPdXCDX+CTxr+tDKWISNRkwiGpuhKOQdRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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