SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df5f30b2e256501535ef3d0488c64d090cb8973ef71409463f50df65127f4863' 
  AND token = 'ttvAr96XiDAxxFB6v5cBqBt6iVatU5BoVQ7M/hTIyvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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