SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39fd356270c3b1cf24384bfb54bfff56094f926b3c063fd4a8715fa9bc991534' 
  AND token = 'ERF8jj7ZAfMpBxVDUfyM97pDDj5oCxGZ4seHXTmQgyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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