SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a71bfacf89fa1526226713760df9ac71bf420c68388a6a143684fc082a0ee27' 
  AND token = 'XiGbLca/XKKIct0z4np0VdpIsgI8UXFzaktpv5/qSn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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