SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7888e1cfb1c54b7f720e749f599ff33aad17b3bb8cf49a3add74cbde567575c3' 
  AND token = 'SEMqQ4skEBUrIgRJ/e+zPYA8MXZggJ/VXJ2vcpx5Iwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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