SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9da912c7b8d12cb394d4bee1f2b455219455835133e198aca04507d93d16bee' 
  AND token = 'niI9eHAx0L2rqR9pU08tVwn03raaTU/msNADxn7jpRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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