SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a90f717ce96fe19e98d2f01d3857797c0d561e1344ca99d0396cdffb1de9cf7' 
  AND token = '6egqh+IMYzjbKZt6hmuzB9YoVGDUp9M6ULzFwq3LUJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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