SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcd4f1cd6c34fc9f152f209739fd60ad3e7f5f6503c08dff7bb160938eaf4b34' 
  AND token = '4tQMD9EXxYqJrK4j2VPwKruGJ/ib0FbrHBxHCzQVdmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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