SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff5d3d9acdac65c365cb69cd47f49bb1d68caba4500f1d1e7a205e8cf9d26520' 
  AND token = 'KgqPoLk4FOJEkVufmESOgo/uHLvlmFQ/UCVZkfcoBwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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