SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dedb1f822c357573a14d7d4ea7fcd37cb747739c18a503f97ff827f15bb4d6e4' 
  AND token = '5OsDF8sg6XGx6h+9HunxQPhvzgGahT/mkssx9C5B87Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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