SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ccfef4bc73b7985d903408b9b2545a8c3b5b62ffbe16f7e04db18979b68591' 
  AND token = 'FRyA6VkyvXKuK3CzjE0V8g6VKFNK3A7TVD+tS/ONphE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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