SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4ca72dd4813aeec144e7a8d19e3911622e65d9dae77e270b305127fa492c9e2' 
  AND token = 'piSABkxORVWZxKj7uv9nMtuIqzVEjKQ8/sDQR1FWXso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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