SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81d4961ee97cfd52cf64a533d09ff2e6e72b3ee743a9132bb415f01a3cc99602' 
  AND token = 'vGhJgbNe+tbYYjiWkQ/1TS5mG0hVSvA5mCTS2Ju/R8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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