SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64d168fbfd3cbc5421e3f2ff9341bc12c55bf292a2501faa0d81cb7a2c3d79d6' 
  AND token = 'nM0InVBZUMFGP7jmiR19okh94rW2ZMeVIKUKsBLWJY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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