SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b34a5f2b7f9adf42481247a09112bca2a609b96fee19ad476e3fb1539a89d035' 
  AND token = '9Z7vKJ4nXLmlIqjr+Jtc0HU6hRI34NAvuK4sgDD3d/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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