SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6a853242bc17d3ac8a6d30e611b7a6d6cb05b391a8c29c426355b578b1cf52a' 
  AND token = 'PJ4ZzffvCUotyemusdB+H4XzRcHNZTNHnKWG9dWFWUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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