SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02dad76e1332163ab4bc85e361b498a80a8e20424e9010acef7a36a7da0b60bc' 
  AND token = 'DXUQC+zyuy8nlO48B9Rsck/ntVjKrhvcMAFOEwE3g9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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