SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e98e2429633ad87c6b6e023909955bec381b757ce4f7c12f858b3501ede737da' 
  AND token = 'x+QtumqzCgnppZGV9ZdNAClsFSvaBpmXj2ypd86N1K8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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