SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a303478f91bbd35086baa7d360620defae06a965bb93a3e8935660d9a72bf923' 
  AND token = '4PxP8bfh5E0vMmtUPFRFaC85YXGQGqgL/+jeJTWUhvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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