SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f29e41495a785147b13720dd7813e700cc1ca3754d19cc5df7df95779da860c8' 
  AND token = 'KuAB/zN3FTQOfLj+8gCPfhG51zBYJGlUw7o/AFZw3s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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