SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8de29f0b5ead451ee294e4ae94bcc6d401c0002450d4f6fd7c0235c983b85383' 
  AND token = 'oKOYSxmx/NGdoC3wvgLgJjey6cAj/KmHC+I7EtN5+LU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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