SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e21c9ecbeaf6b563066bffeb7c36ee9d232ff155e7352423f95327c544560168' 
  AND token = 'j5Em40ls8H6MnfCuY8ado/eaV6+qvPmd5iC7SjrAJ3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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