SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b872cbdc9e1218ca77dfa4b0f25841031a8c47858cdde9f54ee36c2d247e89ab' 
  AND token = 'thY2i3uYZuL7C1rROd5L4FStFrdZsQZBARMlveRNGjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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