SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '06851d151874784b103d3fc3bbcc46f3bbf999d5bce684384f21f863c2858210' 
  AND token = 'NRuAHhBRyqaekyiMSRfKtYFuIhTn6HmaUtYUa+uLvFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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