SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '263a53ce773730a20ce9cb5bb3334d851a8d33a9e72870435127b6644d82ee4f' 
  AND token = 'e4+59lCJ2mdAKZJKuvRia5EFoEVEyRttUcWy8enMuLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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