SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7eae2832e03a706613d365ec78bafe59919e336f405fa9515600dc3e5944cecb' 
  AND token = '+/FB7otVCJL5MRklCHuEY8v+IKgBY1CYUaQdzQyqskA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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