SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '468922cba992321ce80a7a1df52444f1c8d3b4781bbc94492d7efbf692a07952' 
  AND token = '4QNiA5IW8zhQKOoYvD9ZtqjhzVcUoZyZv4srGtNii2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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