SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f35caa6452363787d783995a6a0196ba5a2e1931710950e3f3aaaa97b14b3114' 
  AND token = 'TfFRkKdek2BXuLwQOhYxmM7CpT/AE8qNj0czaIVKrFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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