SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '277a508f6b24db4001daca8e6d66a5b556f7f3271acdf9da66e16d7cc2459d95' 
  AND token = 'iSux3TeZxJPOXebyYYOidpBl4dSjIC9kch3egLWcA/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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