SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f13e81f317e206fcf324312d88e37241d8d3b536c141721c0843ed604473a4bc' 
  AND token = 'lfMIbSnnRjHDUuLHqjwyolVmkQKXeMjloJMmLzHHZsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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