SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae92e1a8d8623eba87fda73806298ed431cdfe31f661d7b8fd80e3bae0d6e6a3' 
  AND token = 'EHZQ03RQFTfAXZ8Zv8csLt8gsMliqBUC7fhilHNrxFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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