SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c91d71f496e18290261748846ca766d3bf77143bbea5424dd054882feb09050' 
  AND token = 'I6TshfmZ1DP9eMnrICf1pD8lWKfhkFgjUXMvgFujZu8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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