SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6893d3ce1366e599a32d45446e17222c597aacc6d673ece3383fc390bb3edaa6' 
  AND token = 'duHZndtWXRKY8qu9B/I+ZSR4PQ1Trte/55HckA97dVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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