SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8bbeec349d238e40dec9ae920801b9261fcd1dbd1730014b491ce0c00ed1596' 
  AND token = 'HlzhSp0xNd0jd8CPyJTgqSYGy1RoDal9ipGtV3NV5/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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