SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c5e93fc5f0130f44e436d8cd07e3824fe4764e7f2229ed12f33fbd7bfc4403' 
  AND token = 'PWkURJeQRDjpOeOvkRlEWnH9PUHsxhtMpVygCyhpBoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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