SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8702bbe91dea614812707722ae6bf49ccd1acb77aa73101ce065e1d3b6ed118' 
  AND token = '4ddZRUPxMsjX62bx2fGhLNXtGf601WLjEkNRUWa0kHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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