SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a281103a379d21b42c9733a37ebb53d3ed54eaf718cf6afe4569ea3639d2ba6f' 
  AND token = 'PVDKcB4c473Su5Hw05SSn6ZLsi0B6GXzsvgbS90E3lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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