SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc00ce50bd4294514eb513c78bac03622026e1c66d1b54c8ea3b0033ce63af7e' 
  AND token = 'hYUfBVTMLN6ec4GJQhiUITryAe+GtvxQQpPXnfLzlr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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