SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1adf6519a0c65b8655859ee002f973a8561e4d413049395662d6f93436688882' 
  AND token = 'cWnS036TnqPbSwCsICQiGFCCQkNzwQPPHHcxgy/qnCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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