SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f43a41ac1e31b6b8865f9d7a418be96f9b6d3963704913bd337ee65911528db' 
  AND token = 'tMZLSUL55+DAEGI2WVHoknNOTDI6TXC+JoOZ+xGeKWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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