SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c55cec3c2f794c17fc54f116fc4f85c06aff5a57a73932ae0de41486ca3c684' 
  AND token = 'um2QeyEO7OkPHJeMd85AiMKhcqyU8N/WGHYUkPDdPzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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