SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4b4983e31efa37e07add595c899927a86185505bc178d417c4ea686e1a0a43b' 
  AND token = 'VMBpqaOmgs2W5A98Po/l1NDJjq/IG+JMztBESYRHclc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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