SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c8bf6b0733c0554297f88b696952e03e0fa6da6e15af7da6632d0a29b71e39e' 
  AND token = '4rKZ/yB84COxFh0nzy2qUJfQjYq/7Oz3j3rvDWAMyvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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