SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9d66664bc57f5b938c3ba5146fcfa4e8c081a8b2dfd819f7709254270b8e20f' 
  AND token = '/VKfFTnESvnADqVMuxjJLxHgFNim00dIXUSIJokzt4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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