SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff2da6568dc0dc8da61fc64a72c66e3c717a19c2015bc9dab218c3557eacdaf4' 
  AND token = 'dLXqlq0OxTa4yBd6hmGiHkPidxM1bIzcGDftHizngAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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