SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a18fcc7cf239273bdef6b2984d2577b00cb38f845230f96bcacfaf8c0927d13' 
  AND token = '4VzYDCbigJbkw96BLzjgsyCw4sGmlCXKC1nKCyh+9jU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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