SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9503c7401d511b122f7b24dad4ebaf529e74909f25a1be88a542c24224ff909' 
  AND token = 'me6F1GOdq/3CypvyAMxhVzimeOYKkfA1AUJo7V/6gxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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