SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '752321dfb2d6f6375e5c5ea5daba93185d9c720e77bff2537136da9cbe1d1332' 
  AND token = 'oT/JA52AgDTg5ixjzKl40mxmB4Z0VfB0RsOijv0lkw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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