SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16166ceeae1025cbcd1fe7c8f30c04a275f8c7fd68e6051b015d3f53f12b4e55' 
  AND token = 's+U3MUNUn0ympWksPLiJxk0tnRcwDHVMnjaZf5swZEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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