SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ce9a6bdd803e48d12510547f8fafe033d990cdf888b53b0e112f26b60c5a821' 
  AND token = 'SQyqpebs90/1TjqC6VzbGXoExDHeXuP3npefGHt/xcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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