SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '750f43f08fc08af3ce6f3268e58366f5ec22c4c211c69d696efed99b92f4d946' 
  AND token = 'o2+0Ki0q4e5aD8wRhEoWZcuuAcGkfhLFzajoPrcJwpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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