SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a73f3ba01d3702f551d8fb87ece89ff91f6032b888c1c9034d7f89915c496610' 
  AND token = 'e9Gt5P/iH0N/UCCO1JcuB6LatVGr+VEIlBCKg1jWDVU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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