SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c9f2c8605fec22640bec142f3093b65c7b098d35f81818a9f9463b0b4e88a73' 
  AND token = 's2VBzYuanBYdj0/dYoHXzjPz0RR5Gdg8BOCYdmYvQGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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