SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a9989c5a8354bc501113d32bcb3fd8e8d3ce8f4403738184482d758da3d6f4d' 
  AND token = 'ko2FtigNrIjp8IR3NN0jFi26yoXxQ2s30Wl8A8dwQuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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