SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68c81c807ba4b6853bda5ade0a3f195574756e2d09a47e92ac03516f7d250f16' 
  AND token = 'UMgvoe1mPHaIwiENljy41VDJjWycNI8wptbcG/BmgnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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