SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e87047b573fcd8414e43442e4bc7c039455c5f95506211ee81b6c3414269267' 
  AND token = 'zTM2VItS1tSXvuzi7RoVErFnZW+aMq9qc3+gwpwoG08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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