SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91a39107bc532964018f7b26f4c93e918c7f51d0d6404004a2f978123cb78904' 
  AND token = 'zG5FlwSip69tGbz7xNkDgCJnr80JnZBw6Uzyw6cHV0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}