SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f3feba26d4fce414efbbcda9117f5701643465fceac09c6ac5c5b80884c4e34' 
  AND token = 'E8/wTKQz2f3/UiVwxo6TEtEtYZ1tAFfZLdSRGKmN5e8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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