SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c012ccf397adbaf7862e2525f72c220243bccb4e3eb688dc9132b6d8a811695' 
  AND token = 'lOb+GUcZoYgxBtktgBwugoyjwpNcbwTAsqlVROmONpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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