SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ca3bf60faa3de3891dacd7b4794566f2ea1394e7129241382768d294004a158' 
  AND token = 'gGHMJTyLIU9ZEHZlwei1ldzV8LPgVbLuiVsfFp+S+B4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}