SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31027a130b8c2bb6266668998093b00b710487fe6eb735e871fb34d52fa81d79' 
  AND token = 'B3bQ91Xtcg60P6Epc73xcEBchHKi76ysXjgOOCwlJMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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