SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c3d9c27b5646f77870c0cd53125842eb0a8d893e883b784998a94c67b71f79b' 
  AND token = 'nYwr7nZ8bgZGvlOBzhLqLWeMR/AaxORsakmdtKLuzJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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