SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3996c3c09637c9d2bc5395fdb9bd94426a9b38a979937bc107568496b71abde5' 
  AND token = 'XYjREBhb7yzBQhPXPr9OLJCJnOJyUvBAfBYBQ8KHZDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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