SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f6287a95ead8629e412221720d0a91852d7d28390c787e7d80a749f64c2ca1a' 
  AND token = '5gOaaBjpjgvTgcQpPCZ/9dnrE0F3h8D1hzqyIyVGzfw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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