SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f3c55eda6c837886d3979abf0b96dcde814f1954f33702ea4852ae50d9f6dbe' 
  AND token = 'hDpXKoBQ4t+nDgrcRHXluzdUiFi8YH3qy2vFnmp0EAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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