SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76ddf91db6f05d85a1065aa72a9e3954b69f37ddd7d671d3cef49c070264878a' 
  AND token = 'msAW8CGodP4e379gnQ9BljukDxjqPo/X5FGBk0zHoP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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