SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b71f590aa81c5ce86570281cc311b0ad36f4fbfdf8801bca64a74190299f1bb5' 
  AND token = 'DI32GtgEUXDWzqWmd9wm+gnKy384nE1kEfXNAK9Qn4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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