SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83dd826351ea9279c15af4b427e0923b9a76820f8cc073cbcfed29dc3e097a10' 
  AND token = 'PKeDIXpmRVOw3V8KeNMRnLJb0ARoIIIkWMNLq6w2YcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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