SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df66b8a3886d6899e3b302f3e055c53bab8480fdcbc092b0d5ba9250bd85112d' 
  AND token = '7ydo7vhZCeaXG2jnwzDeRFurUCFxVpzDmVPfz0KTmD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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