SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f232e9458adf83a5cead901fe29ad1db6d08dfc337d9c88b7c8ddb387e7c2bbc' 
  AND token = '6D1LXably1p5lzIWvHihkVdcrCpNtOA9h6ABwgkdsao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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