SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dede4270e45284304012e76884bcb1ef0daad151730a9cd9606174823effbb6' 
  AND token = 'w23/drGu8djEd3aW+E1ASO//XiLJig+sZWDcjxTWPFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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