SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1292eec4736dfc513a142204b3d094d83b38942dcb4d3db9fb5914d57292bb8c' 
  AND token = '9bKXnvlvEzeHUEPszHSITaimTO/t6GANua79dGVJrpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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