SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac8954c3acb95b993f9596b101d683de6af0fc9df798a18658436845c02a7492' 
  AND token = 'tvsCYVZSgDRhuq5Yw5gn05MqTj0xlKgSLBHVZhEA5A4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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