SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '596822e98ae1fdc4a81a1460531379da6b9527d93c21d5aa2f4ae0dd72e5c348' 
  AND token = 'mipsqFHLk8GNzVQyRV8+NCVsvMkEQkef0HHejOz9e2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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