SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3e3db92e70dd151788174b483123ff97aff539d2955fbb38e3992642523f1b6' 
  AND token = 'JLu/FO6k+jjdIMeBSV/6MAPnMDjDJcjO3UlfuaaJsj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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