SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aaf375fc7bffa1ccaadc41cb888fbd6fd4925d4914ad33382ca7183dccab41d2' 
  AND token = 'h+GuMhbJpAYGpTzUFyZJ1bYZgXfBuCh7gPoNaFQQsUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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