SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3ea644e67cc68a11b8226806b4cb375234d5f8faa063c3331be40913dd159013' 
  AND token = 'sNNUzvg7iNgprg2cvL5QpVHS4+eXZeQqnlFWkBmUSgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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