SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75b14d985fad9a94f5e4c7b26839017f58727a3a435599f638cff0c479a475b3' 
  AND token = 'U8bkXvG4FynjVEHZduKhoZ+PqUH4GQyj37pQy9CpcIA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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