SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '248dcd735a651d68081b87c8f060894d800806d1b3b361d0efb5559aac1c8340' 
  AND token = 'iWEnfb8y/B1R/qjOI6uOidGGrDge8mcQRs5ziXTdNOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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