SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '103619ef7631c10f3490450a480fc1fa2be41948a50f434a27a3d690679928d9' 
  AND token = 'skidTgHsqGG/CEPkgQ5UwuS+yqMJdYLHy5eLUfgzKXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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