SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '847e43609f12af16fb076cbaeeab344b55c4c975167ae9d1af8e1bcc59a4c7ed' 
  AND token = 'prufsQSuIr6d/WQ/kxPNB8ii6NayeymUznylGH+q5bA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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