SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8a1a29296d13dd3c2da72eba6075d7c4547a9723ac9b8f4353407f797db8864' 
  AND token = 'S6SkLpUT8vjzqED42zwnoM5bxNbbxccMEkbEQVSEVY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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