SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acd5f8bca3f3f93a97022192a2f30bed81b3e555d2cf1d3baf9f38b9514ec951' 
  AND token = 'zvYU0kjIz8LutWeSVE0Z0DSOu5CNIbD13HFuh8+aj/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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