SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a3d6306544d022345d34b20437cdc336058d894fc8059528ba42780fc0b6335' 
  AND token = 'K9s9AjLN+lIQKvcSxcq0UMXPkv1eSrLQSEUuW9yZKA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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