SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '321934a566fba91a0c31d9234b900f1c58b07a061292fe40730d9661993e0d4c' 
  AND token = 'RZ7a1jHAgOHNbMgMw/goP9wiFudX1HPEUGmZ+DlrXcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00068

JSON explain

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